EEE

EEE Unit-1 DC Machines MCQ's
MULTIPLE CHOICE QUESTIONS ON UNIT 1: DC MACHINES
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1.The sole purpose of a Commutator in a dc generator is to-------
((A))increase output voltage
((B)) reduce sparking at brushes
((C)) provide smoother output
((D)) convert the induced ac into dc
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Answer : D
2.In a dc generator, the generated emf is directly proportional to the------
((A)) field current
((B)) pole flux
((C)) number of armature parallel paths
((D)) number of dummy coils
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Answer:B
3.An ideal dc generator has .......... voltage regulation.
((A))low
((B))zero
((C))positive
((D))negative
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Answer:B
4.Which generator may have poorest voltage regulation?
((A))series
((B))shunt((C))compound
((D))high
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Answer:A
5.Voltage equation of a dc motor is-----
((A)) V = Eb + IaRa
((B)) Eb = V + IaRa
((C))V = Eb /IaRa
((D))V = Eb + Ia2Ra
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Answer: A
6.Which of the following motor has the constant speed?
((A))Series motor
((B))Shunt motor
((C))Cumulatively compound motor
((D))All of the above
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Answer:B
7.A DC series motor is best for driving-----
((A)) Lathes
((B))Cranes and hoists
((C))Shears and punches
((D)) Machine tools
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Answer:B
8. In a DC series motor increasing the load current will-------
((A))Decrease the speed
((B)) Increase the speed((C))Better commutation
((D)) Increase the back emf
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Answer:A
9. The DC motor, which can provide minimum possible speed regulation at full load without any controller is -------
((A))Series
((B))Shunt
((C))Cumulative Compound
((D)) Differential Compound
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Answer:B
10. In 8 - pole wave connected motor armature, the number of parallel paths are------
((A))8
((B)) 4
((C)) 2
((D))1
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Answer:C
11. The d.c. series motor should always be started with load because______
((A)) at no load, it will rotate at dangerously high speed.
((B)) it will fail to start.
((C)) it will not develop high starting torque.
((D)) all are true.
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Answer:A
12. In a d.c. machine, the armature mmf is--------------((A))stationary w.r.t. armature.
((B)) rotating w.r.t. field.
((C)) stationary w.r.t. field.
((D)) rotating w.r.t. brushes.
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Answer:C
13. The speed of a d. c series motor at no load is-------------
((A)) zero
((B))dangerously high
((C)) very low
((D))can’t be said
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Answer:B
14. The function of commutator in a d. c machine is------
((A)) to change direction of rotation
((B))to change alternating voltage to direct voltage
((C)) to provide easy control of voltage
((D)) to protect the machine from overcurrents
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Answer:B
15. A sinusoidal voltage of frequency 1 Hz is applied to the field of a d.c generator. The armature voltage will be-----------
((A))1 Hz square wave
((B))1 Hz sine wave
((C)) d. c voltage
((D)) zero
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Answer:B
16. The direction of rotation of a dc series motor can be reversed----------((A)) by interchanging the supply terminals
((B)) by interchanging the field terminals
((C)) either option A or option B .
((D)) none of the above
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Answer:B
17. A dc shunt generator driven at normal speed in the normal direction fails to build up armature voltage because------
((A)) the armature resistance is high
((B)) the field current is not sufficiently high
((C)) there is no residual magnetism.
((D)) the field resistance is low
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Answer:C
18. If a dc motor is connected across an ac supply, the dc motor will-----------
((A)) burn as the eddy currents in the field produces heat
((B)) run at its normal speed
((C)) run at a lower speed
((D)) can’t be said
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Answer:A
19. What would happen if the field of dc shunt motor is opened?
((A))the speed of the motor will be reduced
((B)) it will run at its normal speed
((C)) the speed will be enormously high , and the motor will destroy itself
((D))the motor will come to hault
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Answer:C20. Which one of the following motors is used in a locomotive?
((A)) Induction motor
((B))DC series motor
((C)) Synchronous motor
((D))Shaded pole motor
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Answer:B
21.The dummy coil in the dc machine is used to------------
((A))eliminate armature reaction
((B)) bring about mechanical balance of armature
((C)) eliminate reactance voltage
((D))reduce wear and tear
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Answer:B
22.The mechanical power developed by the dc motor is maximum when-------
((A))back emf = applied voltage
((B)) back emf = 0
((C)) back emf = 0.5 times the applied voltage
((D)) at the starting of motor
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Answer:C
23.The armature torque of the dc shunt motor is proportional to------
((A)) armature current only
((B)) field flux only
((C)) armature current and field flux both
((D)) none of the above
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Answer:C24. The reversal of speed of motors used as electric braking is known as----
((A)) regenerative braking
((B)) plugging
((C)) dynamic braking
((D)) static braking
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Answer:B
25. The output power of any electrical motor is taken from the--------
((A)) Armature
((B))Field
((C))Coupling mounted on the shaft
((D)) Motor frame
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Answer:C
26. If the back emf in a dc motor varnishes suddenly, then the motor------
((A)) Run at very high speeds
((B)) Start hunting
((C)) may burn
((D)) come to stall
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Answer:C
27. The direction of the armature current in a dc motor is--------------
((A))The same as the generated emf
((B)) Opposite to that of generated emf
((C)) Not dependent upon the direction of the armature emf
((D)) None of the above
Hide !Answer:B
28. When a dc machine is connected to the dc supply mains it will produce-----
((A)) EMF in opposition to the applied voltage
((B))EMF in phase with the applied voltage
((C)) EMF decreases with time
((D)) None of the above
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Answer:A
29. The direction of rotation of a dc motor can be determined by-----
((A)) Fleming's right hand rule
((B)) Fleming's left hand rule
((C)) Lenz's law
((D)) Ampere's law
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Answer:B
30. A thick wire is used in dc series motor field winding than that in dc shunt motor------
((A)) To create more flux
((B)) To reduce the resistance
((C)) To carry large load current
((D)) Both (b) and (c)
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31. An electric train employing a dc series motor is running at the fixed speed. When a sudden slight drop in the mains voltage occurs, this would result in------
((A)) Drop in the speed and rise in the current
((B)) Rise in the speed and drop in the current
((C)) Rise in the speed and rise in the current
((D)) Drop in speed with current unalteredHide !
Answer:A
32. A DC shunt motor is driving a constant torque load. On inserting an additional resistance in the armature circuit, the speed of the motor will-----
((A)) Remains unchanged
((B)) Increases
((C)) Decreases
((D)) Be Zero
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Answer:C
Show Answer
33. A DC series motor is best suited for electrical traction because-----------
((A)) It develops high starting torque
((B)) It runs at very high speed
((C)) It is cheaper in cost
((D)) It is more rugged in construction like induction motor
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Answer:A
34. A DC series motor is used for overhauling load. It can work stable if------
((A))The armature is shunted by a resistor
((B))The field winding is reversed
((C)) A resistor is put in series with the machine
((D)) A divertor is put across the field
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Answer:A
35. Which of the following dc motors has maximum self relieving property?
((A))Shunt
((B)) Series((C))Cumulative compound
((D)) Differential compound
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Answer:B
36. When the direction of power flow in a differential compounded motor reverses, it will operate as a---------
((A)) Cumulative compound generator
((B)) Differential compound generator
((C)) Series motor
((D)) Shunt motor
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Answer:A
37. A separately excited dc generator is feeding dc shunt motor. If the load torque on the motor is halved approximately, then------
((A)) Armature current of both motor and generator are halved
((B)) Armature current of motor is halved and that of the generator is unaltered
((C)) Armature current of generator is halved and that of the motor is unaltered
((D)) Armature current of both motor and generator are unaltered
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Answer:A
38. A flywheel is employed with a dc compound motor to reduce the peak demand, the compound motor should be--------
((A)) Level compound
((B)) Differential compound
((C)) Cumulative compound
((D)) None of the above
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Answer:C
39. The flux leakage coefficient in dc machine is usually-------
((A)) 0.6 to 0.8((B)) 1.05
((C)) 1.1 to 1.3
((D)) 2 to 2.5
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Answer:C
40. The d.c. series motor should always be started with load because----
((A)) at no load, it will rotate at dangerously high speed.
((B)) it will fail to start.
((C)) it will not develop high starting torque.
((D)) all are true.
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Answer:A
41. The speed of a dc motor can be controlled by varying_________
((A))its flux per pole
((B))resistance of armature circuit
((C))applied voltage
((D)) all of the above
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42. In a DC motor, unidirectional torque is produced with the help of________
((A))Brushes
((B)) Commutator
((C)) End-plates
((D)) Both a and b
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43. The counter emf of dc motor__________
((A)) Often exceeds the supply voltage
((B))Aids the applied voltage
((C))Helps in energy conversion((D)) Regulates its armature voltage
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Answer:C
44. The \frac{Eb}{V} ratio of a dc motor is an indication of its------------
((A))Efficiency
((B))Speed regulation
((C))Starting torque
((D)) Running Torque
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Answer:A
45. The induced emf in the armature conductors of a dc motor is---------
((A))Sinusoidal
((B)) Trapezoidal
((C)) Rectangular
((D)) Alternating
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Answer:A
46. A dc motor can be looked upon as dc generator with the power flow__________
((A)) Reduced
((B)) Reversed
((C)) Increased
((D)) Modified
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Answer:B
47. A series motor is best suited for driving------
((A))Lathes
((B)) Cranes and hoists((C))Shears and punches
((D)) Machine tools
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Answer:B
48. The \frac{Ta}{Ia} graph of a dc series motor is a___________-
((A))Parabola from no load to overload
((B))Straight line throughout
((C))Parabola throughout
((D)) Parabola upto full load and a straight line at overloads
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49. When load is removed, .......motor will run at the highest speed.
((A))Shunt
((B)) Cumulative - compound
((C))Differential compound
((D)) Series
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50. In a d.c. series motor the electromagnetic torque developed is proportional to________
((A)) Ia
((B)) Ia2
((C))Ia^{3}
((D))\sqrt{Ia}
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Answer:B
51. The armature core of a dc machine is laminated to reduce----
((A)) Eddy current loss
((B)) Hysteresis loss((C)) copper losses
((D)) friction and windage losses
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Answer:A
52. A drawback of a dc series motor is its---------
((A)) low starting torque
((B))constant speed
((C))speed runaway
((D))high starting torque
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Answer:C
53. If the back emf in a dc motor vanishes suddenly, then the motor__________
((A))run at very high speeds
((B)) start hunting
((C)) will burn
((D))come to stall
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Answer:C
54. The direction of the armature current in a dc motor is___________
((A)) The same as the generated emf
((B))Opposite to that of generated emf
((C)) Not dependent upon the direction of the armature emf
((D)) None of the above
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Answer:B
55. When a dc machine is connected to the dc supply mains, it will produce__________
((A)) EMF in opposition to the applied voltage((B)) EMF in phase with the applied voltage
((C)) EMF decreases with time
((D)) None of the above
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Answer:A
56. The speed of a d.c. motor may be increased by_____________
((A)) increasing the armature current
((B)) decreasing the field current
((C)) Decreasing the applied voltage
((D)) increasing the field current
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Answer:B
57. The armature resistance of a d.c. shunt motor is 0.5 ohm, the supply voltage is 200V and the armature current at start can be__________
((A)) 4A
((B)) 8 A
((C)) 400 A
((D)) 392 A
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Answer:C
58. In d.c. generators iron losses are made up of__________
((A)) hysteresis and friction losses
((B)) hysteresis, eddy current and brush contact losses
((C)) hysteresis and eddy current losses
((D)) hysteresis, eddy current and copper Losses
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Answer:C
59. The effect of inserting a resistance in series with the field winding of a shunt motor is to__________
((A)) increase the magnetic field((B)) increase the speed of the motor
((C))to reduce power losses
((D))to increase efficiency of motor
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Answer:B
((Q))_2// In a dc shunt motor; the terminal voltage is halved while the torque is kept constant. The resulting approximate variation in speed 'N' and armature
current ' Ia ' will be
((A)) Both N and Ia are doubled.
((B)) N is constant and Ia is doubled.
((C)) N is doubled while Ia is halved.
((D)) N is constant but Ia is halved.
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Answer:B
60. A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the terminal voltage of 220V. If the same machine is run as a motor it takes
a line current of 20A from 220V supply. The speed of the machine as a motor will be___________
((A)) 800 rpm.
((B)) more than 800 rpm.
((C)) less than 800 rpm.
((D)) both higher or lower than 800 rpm.
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Answer:C
61. A 4 pole lap wound dc shunt motor rotates at the speed of 1500 rpm, has a flux of 0.4 mWb and the total number of conductors are 1000. What is the value
of emf?
((A)) 100 Volts.
((B)) 0.1 Volts.
((C)) 1 Volts.
((D)) 10 Volts.
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62. The torque, in a _____________is proportional to the square of the armature current.
((A)) DC shunt motor
((B)) Induction motor
((C)) AC motor
((D)) DC series motor
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63. A commutator in a d.c. machine___________
((A)) reduces power loss in armature.
((B)) reduces power loss in field circuit.
((C)) converts the induced a.c armature voltage into direct voltage.
((D)) is not necessary.
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Answer:C
64. The speed of a d.c. shunt motor at no-load is________ higher than its speed at rated load.
((A)) 5 to 10%
((B)) 15 to 20%
((C)) 25 to 30% (
((D)) 35 to 40%
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Answer:A
((Q))A d.c. shunt motor runs at no load speed of 1140 r.p.m. At full load, armature reaction weakens the main flux by 5% whereas the armature circuit voltage
drops by 10%. The motor full load speed in r.p.m. is____________
((A)) 1080
((B)) 1203
((C)) 1000
((D)) 1200Hide !
Answer:A
((Q))The introduction of interpoles in between the main pole improves the performance of d.c. machines, because__________
((A)) The interpole produces additional flux to augment the developed torque.
((B)) The flux waveform is improved with reduction in harmonics.
((C)) The inequality of air flux on the top and bottom halves of armature isremoved.
((D)) A counter e.m.f. is induced in the coil undergoing commutation.
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((Q))In DC generators, armature reaction is produced actually by_________
((A)) Its field current.
((B)) Armature conductors.
((C)) Field pole winding.
((D)) Load current in armature.
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((Q))As compared to shunt and compound DC motors, the series DC motor will have the highest torque because of its comparatively ____________ at the start.
((A)) Lower armature resistance.
((B)) Stronger series field.
((C)) Fewer series turns.
((D)) Larger armature current.
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((Q))The armature of a dc machine is laminated to reduce:
((A)) Eddy current loss
((B)) Hysteresis loss
((C)) copper losses((D)) friction and windage losses
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Answer:A
((Q))Application of DC motors is generally restricted to a few load speed applications because of _____.
((A)) cost of the motor is high
((B)) problems with mechanical commutation
((C)) Maintenance problems
((D)) None of the above
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Answer:B
((Q)) Which of the following information available on name plate of a motor?
((A)) HP rating
(( B)) RPM
((C )) Frame model
((D)) all the above
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(Q)) Machine tools are a typical example of____________.
((A)) Constant power load
((B)) Constant torque load
((C)) Variable torque load
((D)) Both A and B
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((Q)) In Fleming's right-hand rule, the thumb point towards________
((A)) direction of flux
((B)) direction of induced e.m.f.
((C))direction of motion of conductor, if forefinger points along the lines of flux((D) direction of motion of the conductor if forefinger point in the direction of generated e.m.f.
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Answer:C
((Q)) The resistance of armature winding depends on________
((A)) number of conductors
((B)) number of poles
((C)) cross-sectional area of conductor.
((D)) all of above
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Answer:C
((Q)) The output voltage of a simple d.c. generator is____________
((A)) a.c. square wave.
((B)) a.c. sinusoidal wave
((C)) pure d.c,
((D)) pulsating d.c.
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((Q)) In shunt generator interpole winding carries,_________
((A)) armature current
((B)) shunt field current
((C)) full load current
((D)) none of these
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((Q)) Due to which of the following reasons a separately excited generator as compared to a self-excited generator is better?
((A)) is more stable
((B)) has exciting current independent of load current((C)) is amenable to better voltage
((D)) has all above features.
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((Q)) Due to which of the following reasons, copper brushes in D.C. machine are used?
((A)) when high voltage and small currents are involved
((B)) when low voltage and high currents are involved
((C)) in both of the above cases
((D) in none of the above cases.
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Answer:C
((Q)) To maintain constant d.c. voltage at the consumers' terminals the generator used is______.
((A)) series generator
((B)) over compounded generator
((C)) under compounded generator
((D)) flat compound generator
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((Q))A four pole lap wound d.c. shunt generator is supplying 46 A to a load. The field current of the generator is 2A. The current per parallel path is___________
((A)) 12 A
((B)) 24 A
((C)) 24 A
((D)) none of these
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Answer:A
((Q))What would be observed if a d.c. shunt motor is started with an open-circuited field?
((A)) The motor pick up fast and acquires full speed while drawing small current
((B)) The motor picks up fast and acquires full speed while drawing large current((C)) The motor does not pick up speed but draws is large current
((D)) The motor does not pick up speed but draws a small current
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Answer:B
((Q))When the series field is so connected that its ampere turns act in the same direction as those of shunt field, the generator is said to be__________
((A)) series generator
((B)) Shunt generator
((C)) cumulatively compound generator
((D)) differentially compound generator
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Answer:C
((Q))What is the nature of a d.c. machine?
((A)) pure d.c.
((B)) alternating
((C)) pulsating d.c.
((D)) rectified a.c.
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((Q)) Why is the armature of a d.c. machine made of silicon steel stampings?
((A)) to reduce eddy current loss
((B)) to reduce hysteresis loss.
((C)) for the ease with which the slots can be created
((D)) Both A and B
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((Q)) Due to which of the following reasons a twelve pole, lap wound d.c. generator be preferred to four-pole lap wound d.c. generator?
((A)) low speed.((B)) high speed
((C)) higher voltage
((D)) higher current output.
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((Q))The armature coils of a d.c. machine are not made of aluminium, because________
((A)) aluminium is costly
((B)) aluminium has low resistivity
((C)) the thermal conductivity of aluminium low
((D)) the size of the machine will become more
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((Q))Brushes of D.C. machines are usually made of__________.
((A)) hard copper
((B)) soft copper
((C)) carbon
((D)) all of above
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Answer:C
(Q)) In the output voltage of a d.c. generator the ripple effects can be reduced by increasing the__________.
((A)) field current
((B)) number of armature coils .
((C)) number of turns in the field winding
((D)) size of the conductor of the armature coil
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Answer:B
((Q))Which of the following factors does not govern the iron losses in a D.C. machine?
((A)) load.((B)) voltage
((C)) speed
((D)) speed and voltage
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Answer:A
((Q))The armature core of a d.c. machine is usually made of laminated sheets in order to
((A)) reduce hysteresis loss
((B)) reduce armature copper losses.
((C)) reduce eddy current
((D)) increase its surface area for better dissipation of heat
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Answer:C
((Q))The polarity of the interpoles in d.c. generator_________.
((A)) is neutral as these poles do not play part in generating e.m.f.
((B)) is the same as that of the main pole ahead
((C)) is the same as that of the immediately preceding pole
((D)) is opposite to that of the main pole ahead
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((Q)) With given power rating for lower current and higher voltage rating of a d.c. machine, one should prefer_________.
((A)) lap winding
((B)) wave winding
((C)) none of these
((D)) any of these
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Answer:B
((Q)) Compound generator is said to be flat compounded if the full load voltage is((A)) more than the no-load voltage
((B)) less than the no-load voltage
((C)) exactly half of the no-load voltage,
((D)) equal to no-load voltage
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Answeremoticon_grin
((Q)) The decrease in terminal voltage of a shunt generator from, no load condition is due to_________.
((A)) decrease in field current
((B)) armature reaction
((C)) armature resistance drop
((D)) all of these
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((Q)) Commutation in a d.c. generator causes___________.
((A)) d.c. changes to a.c.
((B)) d.c. changes to d.c.
((C)) a.c. changes to d.c.
((D)) changes to high voltage d:c.
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Answer:C
((Q)) In D.C. machines lap winding is used for___________
((A)) low voltage, low current
((B)) low voltage, high current
((C)) high voltage, low current
((D)) high voltage, high current
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Answer:B
((Q)) The yoke of a d.c. machine is made up of____________((A)) copper-zinc alloy
((B)) insulating material
((C)) comparatively poor magnetic material
((D)) very high permeability magnetic material
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((Q)) The commutator segments of a d.c. machine are usually made of________
((A)) carbon
((B)) iron
((C)) hard drawn copper
((D)) stainless steel
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Answer:C
((Q)) The e.m.f. generated in the armature of d.c. generator is directly proportional to
((A)) number of poles
((B)) speed of armature
((C)) flux/pole
((D)) all of the above
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Answeremoticon_grin
((Q)) In the armature, D.C. generator induces__________.
((A)) oscillating e.m.f.
((B)) a.c. voltage,
((C)) a.c. superimposed over d.c.
((D)) d.c. voltage
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Answer:B((Q)) Which type of d.c. generator is used to charge the batteries?
((A)) shunt generator
((B)) series generator
((C)) long shunt compound generator
((D)) any of the-above
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Answer:A
((Q)) If the the number of poles in a wave wound generator is doubled then the generated e.m.f. will__________.
((A)) become half
((B)) become double
((C)) increase to four times
((D)) remain constant
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Answer:B
((Q)) If the number of poles in a lap wound generator be doubled, then the generated e.m.f will_________.
((A)) become half
((B)) become double
((C)) increase to four times
((D)) remain constant
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Answeremoticon_grin
((Q)) Which of the following d.c. generator can build up without any residual magnetism in the places ?
((A)) compound generator
((B)) separately excited generator
((C)) series generator
((D)) shunt generator
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Answer:B((Q)) The polarity of a D.C. generator can be reversed by___________
((A)) increase field current
((B)) reversing the field current
((C)) reversing field current as well as direction of rotation
((D)) any of the above
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Answer:B
((Q)) In d.c. machine, interpoles are used to_________
((A)) generate more e.m.f. in the armature
((B)) avoid interference of the armature flux with the main flux
((C)) increase the demagnetising effect of armature reaction
((D)) neutralise the effect of armature reaction in the interpole region
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Answer:A
((Q)) In D.C. generators, current to the external circuit from armature comes out from
((A)) slip rings
((B)) commutator
((C)) brush connection
((D)) none of above
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Answer:C
((Q)) The material for commutator is generally__________
((A)) carbon
((B)) mica
((C)) copper
((D)) cast iron
Hide !Answer:C
((Q)) The sparking at the brushes of a d.c. generator is due to________.
((A)) reactance voltage
((B)) light load
((C)) armature reaction
((D)) high resistance of the brushes
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Answer:A
((Q)) While pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be_________.
((A)) half
((B)) twice
((C)) nominal value
((D)) slightly less than nominal
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Answer:B
((Q)) Which would have the highest percentage of voltage regulation?
((A)) series generator
((B)) shunt generator
((C)) compound generator
((D)) separately excited generator
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Answer:A
((Q)) The efficiency of a d.c. machine is maximum when__________.
((A)) variable losses are equal to constant losses
((B)) stray losses are equal to copper losses
((C)) field copper losses are equal to armature copper losses
((D)) magnetic losses are equal to windage lossHide !
Answer:A
((Q)) The efficiency of a d.c. shunt generator becomes maximum when the__________
((A)) stray losses are equal to constant losses
((B)) armature copper losses are equal to constant losses
((C)) magnetic losses are equal to mechanical losses
((D)) field copper losses are equal to constant losses
Hide !
Answer:B
((Q)) Series field resistance of a d.c. series generator is about__________
((A)) 0.1 Ω
((B)) 2.5 Ω
((C)) 10 Ω
((D)) 200 Ω
Hide !
Answer:A
((Q)) Which of the following d.c. motor has approximately constant speed? ,
((A)) shunt motor
((B)) series motor
((C)) cumulatively compound motor
((D)) all of the above
Hide !
Answer:A
((Q)) If the supply voltage in a shunt motor is increased, which of the following will decreased?
((A)) full load current
((B)) full load speed
((C)) starting torque
((D)) none of the aboveHide !
Answeremoticon_grin
((Q)) Which device changes the alternating e.rn.f. generated by the d.c. generator in its armature coil, to d.c. ?
((A)) slip ring
((B)) rectifier
((C)) rotary conventor
((D)) commutator
Hide !
Answeremoticon_grin
((Q)) If the d.c. series motor is started at no load, it will_________.
((A)) run at very high r.p.m.
((B)) run with.excessive noise
((C)) burn out
((D)) not start
Hide !
Answer:A
((Q)) A shunt generator supplies 9A of load current at 400 V. If its armature resistance is 1 Ω and field current is 1 A, then the generated e.m.f. will
be________
((A)) 400 Volts.
((B)) 409 Volts
((C)) 410 Volts
((D)) none of these
Hide !
Answer:C
((Q)) Stray losses in d.c. machine are_________
((A)) windage loss
((B)) magnetic losses
((C)) mechanical losses.((D)) all of these
Hide !
Answeremoticon_grin
((Q)) Which of the following type of d.c. motor is least used?
((A)) series motor
((B)) differentially compound motor
((C)) permanent magnet motor
((D)) cumulative compound motor
Hide !
Answer:B
((Q)) Which of the following parts of a d.c. motor can sustain the maximum temperature rise?
((A)) slip rings
((B)) commutator
((C)) field windings
((D)) armature windings
Hide !
Answer:B
((Q)) In a d.c. machine constant losses composed of
((A)) mechanical losses
((B)) commutator losses
((C)) iron losses and mechanical losses
((D)) total copper losses of the machine
Hide !
Answer:C
((Q)) In a d.c. machine variable losses are composed of
((A)) iron losses
((B)) mechanical losses((C)) shunt field copper losses
((D)) armature copper losses
Hide !
Answeremoticon_grin
((Q)) If the resistance of the field winding of a D.C. generator is increased, the output voltage will____________
((A)) fluctuate heavily
((B)) remain unaffected
((C)) increase
((D)) decrease.
Hide !
Answeremoticon_grin
((Q)) Brushes in d.c. machines are always placed along___________.
((A)) geometrical neutral axis (GNA)
((B)) magnetic netural axis (MNA)
((C)) (a) and (b) both
((D)) none of the above
Hide !
Answer:B
((Q)) In the commutation process___________
((A)) voltage is revised
((B)) current is reversed in the field coil
((C)) current is reversed in the armature coil undergoing commutation
((D)) both Armature current and voltage are reversed
Hide !
Answer:C
((Q)) The load current of a d.c. series motor is 50 A, when supplying of a full load torque. If the current is reduced to 25 A, the torque will be_________
((A)) 25% of full load torque
((B)) 50% of full load torque((C)) 15% of full load torque
((D)) same as full load torque
Hide !
Answer:A
((Q)) What is the function of commutator of the d.c. motor?
((A)) to reduce friction
((B)) to convert a.c. into d.c.
((C)) to convert d.c. into a.c
((D)) to feed the current to the armature
Hide !
Answeremoticon_grin
((Q)) Which of the following loads normally start at rated torque?
((A)) crane
((B)) centrifugal pumps
((C)) industrial blowers
((D)) conveyors and printing presses
Hide !
Answer:C
((Q)) A punching machine, having intermittent light and heavy loads, should have
((A)) shunt motor
((B)) series motor.
((C)) differentially compound motor
((D)) cumulatively compound motor
Hide !
Answeremoticon_grin
((Q)) The Voltage between commutator segments should not exceed than
((A)) 2 volts((B)) 15 volts
((C)) 50 volts
((D)) 200 volts
Hide !
Answer:A
((Q)) On increasing the load on d.c. series generator its terminal voltage will________
((A)) increase
((B)) decrease slightly
((C)) decrease sharply
((D)) remain same.
Hide !
Answer:C
((Q)) What is the flux in the armature core section of a dc machine if the air gap flux be ø Wb?
((A)) ø
((B)) 0.1 ø
((C)) 1.5 ø
((D)) ø /2
Hide !
Answer:A
((Q)) Full load speed of a d.c. motor is 1000 rpm and speed regulation being 90%, no load speed will be_________
((A)) 900 r.p.m.
((B)) 1000 r.p.m.
((C)) 1100 r.p.m.
((D)) none
Hide !
Answeremoticon_grin
((Q)) Yoke of a d.c. generator is made of______.
((A)) wood((B)) copper
((C)) cast iron
((D)) aluminium
Hide !
Answer:C
((Q)) A d.,c. shunt motor, running at light load, if the field winding gets opened, what will happen ?
((A)) motor will stop instantly
((B)) motor will take heavy input current
((C)) motor will make mechanical noise
((D)) motor will tend to pick up high speed
Hide !
Answeremoticon_grin
((Q)) A d.c. series motor__________
((A)) a ways runs at constant speed
((B)) should always be started on load
((C)) may stop if the field gets opened
((D)) is not suitable for high starting torque
Hide !
Answer:B
((Q)) Which of the following components is a must for d.c. motor?
((A)) armature
((B)) commutator
((C)) slipping
((D)) type of winding
Hide !
Answer:B
((Q)) Which type of d.c. motor is preferred for cranes end hoists?((A)) series motor
((B)) shunt motor
((C)) cumulatively compound motor
((D)) any of the above
Hide !
Answer:A
((Q)) Which of the following regulation is preferred for d.c. generator?
((A)) 50% regulation
((B)) 100% regulation
((C)) very low regulation
((D)) infinite regulation
Hide !
Answer:C
((Q)) Armature resistance of a d.c. machine is about
((A)) 0.1 Ω
((B)) 25 Ω
((C)) 200 Ω
((D)) none of these
Hide !
Answer:A
((Q)) The resistance of Shunt winding of a d.c. machine may be about________
((A)) 0.1 Ω
((B)) 1 Ω
((C)) 250 Ω
((D)) none of these
Hide !
Answer:C
((Q)) In shunt motor, armature current is equal to__________((A)) load current
((B)) the sum of motor current and field current
((C)) the difference of motor current and field current
((D)) both motor and field current
Hide !
Answer:C
((Q)) A series motor has________
((A)) widely varying speed
((B)) approximately constant speed at all loads
((C)) low speed at high loads and high speed at low loads
((D)) high speed at 'high loads add low speed at low loads
Hide !
Answer:A
((Q)) What is the current drawn by a 220 V d.c. motor of armature resistance 0.5 Ohm and back e.m.f. 200 V?
((A)) 4 A
((B)) 20 A
((C)) 40 A
((D)) 110 A
Hide !
Answer:C
Answer:C
((Q)) On which of the following principle does the d.c. motor work?
((A)) corkscrew rule
((B)) right hand thumb rule
((C)) Fleming's left hand rule
((D)) Fleming’s right hand ruleHide !
Answer:C
((Q)) If residual magnetism is not present in a d.c. generator, the induced e.m.f. at zero speed_________
((A)) zero
((B)) unpredictable
((C)) 10% rated voltage
((D)) the same as rated voltage
Hide !
Answer:A
((Q)) The armataure resistance of a 200 V d.c. machine is 0.5 ohm. If the full load armature current is 50 A, what will be the induced e.m.f. when, the machine
acts as information generator (ii) motor will be__________
((A)) 230 V, 170 V
((B)) 210 V, 190 V
((C)) 225 V, 175 V
((D)) 202.5 V, 197.5 V
Hide !
Answer:C
((Q)) Which motor will have least percentage increase of input current for the same percentage increase in torque?
((A)) shunt motor
((B)) series motor
((C)) cumulatively compound motors
((D)) separately excited motor
Hide !
Answer:B
((Q)) Which of the following information available on name plate of a motor?
((A))HP rating
((B)) Frame model
((C)) RPM((D)) All of the above
Hide !
Answeremoticon_grin
((Q)) The d.c. series motor should always be started with load because
((A)) at no load, it will rotate at dangerously high speed.
((B)) it will fail to start.
((C)) it will not develop high starting torque.
((D)) all are true.
Hide !
Answer:A
((Q)) In a d.c. machine, the armature mmf is
((A)) stationary w.r.t. armature.
((B)) rotating w.r.t. field.
((C)) stationary w.r.t. field.
((D)) rotating w.r.t. brushes.
Hide !
Answer:C
((Q)) A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the
terminal voltage of 220V. If the same machine is run as a motor it takes a line current of 20A from 220V supply. The speed of the machine as a motor will
be_________.
((A)) 800 rpm.
((B)) more than 800 rpm.
((C)) less than 800 rpm.
((D)) both higher or lower than 800 rpm.
Hide !
Answer:C
((Q)) A 4 pole lap wound dc shunt motor rotates at the speed of 1500 rpm, has a flux of 0.4mWb and the total number of conductors are 1000. What is the value
of emf?((A)) 100 Volts.
((B)) 0.1 Volts.
((C)) 1 Volts.
((D)) 10 Volts.
Hide !
Answeremoticon_grin
((Q)) The torque, in a _____________is proportional to the square of the armature current.
((A)) DC shunt motor
((B)) DC series motor
((C)) Separately excited motor
((D)) Differential compound motor
Hide !
Answer:B
((Q)) A commutator in a d.c. machine___________.
((A)) Reduces power loss in armature.
((B)) Reduces power loss in field circuit.
((C)) Converts the induced a.c armature voltage into direct voltage.
((D)) Is not necessary.
Hide !
Answer:C
((Q)) The speed of a d.c. shunt motor at no-load is__________ higher than its speed at rated load.
(A) 5 to 10%
(B) 15 to 20%
(C) 25 to 30%
(D) 35 to 40%
Hide !
Answer:A((Q)) A d.c. shunt motor runs at no load speed of 1140 r.p.m. At full load, armature reaction weakens the main flux by 5% whereas the armature circuit voltage
drops by 10%. The motor full load speed in r.p.m. is__________.
((A)) 1080
((B)) 1203
((C)) 1000
((D)) 1200
Hide !
Answer:A
((Q)) In DC generators, armature reaction is produced actually by_________.
(A) Its field current.
(B) Armature conductors.
(C) Field pole winding.
(D) Load current in armature.
Hide !
Answeremoticon_grin
((Q)) As compared to shunt and compound DC motors, the series DC motor will have the
highest torque because of its comparatively ____________ at the start.
((A)) Lower armature resistance.
((B)) Stronger series field.
((C)) Fewer series turns.
((D)) Larger armature current.
Hide !
Answeremoticon_grinEEE Unit-2 Three Phase Induction
Motors MCQ's
1. Which of the following component is usually fabricated out of silicon steel?
Bearings
Shaft
Stator core
None of the above
Hide !
Answer: c
2. The frame of an induction motor is usually made of
silicon steel
cast iron
alluminium
bronze
Hide !
Answer: b
3. The shaft of an induction motor is made of
stiff
flexiblehollow
any of the above
Hide !
Answer: a
4. The shaft of an induction motor is made of
high speed steel
stainless steel
carbon steel
cast iron
Hide !
Answer: c
5. In an induction motor, no-load the slip is generally
less than 1%
1.5%
2%
4%
Show Answer
6. In medium sized induction motors, the slip is generally around
0.04%
0.4%
4%14%
Show Answer
7. In squirrel cage induction motors, the rotor slots are usually given slight skew in order to
(a) reduce windage losses
(b) reduce eddy currents
(c) reduce accumulation of dirt and dust
(d) reduce magnetic hum
Hide !
Answeremoticon_grin
8. In case the air gap in an induction motor is increased
the magnetising current of the rotor will decrease
the power factor will decrease
speed of motor will increase
the windage losses will increase
Hide !
Answer:B
9. Slip rings are usually made of
copper
carbon
phosphor bronze
aluminiumHide !
Answer:C
10. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be
200 Hz
50 Hz
2 Hz
0.2 Hz
Show Answer
11. In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be
Ns
s.N,
(l-s)Ns
(Ns-l)s
Hide !
Answer:C
12.The efficiency of an induction motor can be expected to be nearly
60 to 90%
80 to 90%
95 to 98%99%
Hide !
Answer:B
13. The number of slip rings on a squirrel cage induction motor is usually
two
three
four
none
Hide !
Answeremoticon_grin
14. The starting torque of a squirrel-cage induction motor is
low
negligible
same as full-load torque
slightly more than full-load torque
Hide !
Answer:A
15. A double squirrel-cage induction motor has
two rotors moving in opposite direction
two parallel windings in stator
two parallel windings in rotortwo series windings in stator
Hide !
Answer:C
16. Star-delta starting of motors is not possible in case of
single phase motors
variable speed motors
low horse power motors
high speed motors
Hide !
Answer:A
17. The term 'cogging' is associated with
three phase transformers
compound generators
D.C. series motors
induction motors
Hide !
Answeremoticon_grin
18. In case of the induction motors the torque is
inversely proportional to (Vslip)
directly proportional to (slip)2
inversely proportional to slipdirectly proportional to slip
Hide !
Answeremoticon_grin
19. An induction motor with 1000 r.p.m. speed will have
8 poles
6 poles
4 poles
2 poles
Hide !
Answer:B
20. The good power factor of an induction motor can be achieved if the average flux density in the air gap is
absent
small
large
infinity
Hide !
Answer:B
21. An induction motor is identical to
D.C. compound motor
D.C. series motor
synchronous motorasynchronous motor
Hide !
Answeremoticon_grin
22. The injected e.m.f. in the rotor of induction motor must have
zero frequency
the same frequency as the slip frequency
the same phase as the rotor e.m.f.
high value for the satisfactory speed control
Hide !
Answer:B
23. Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor ?
By changing the number of stator poles
Rotor rheostat control
By operating two motors in cascade
By injecting e.m.f. in the rotor circuit
Hide !
Answer:A
24. The crawling in the induction motor is caused by
low voltage supply
high loads
harmonics develped in the motorimproper design of the machine
none of the above
Hide !
Answer:C
25. The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type
star connected only
delta connected only
(a) and (b) both
none of the above
Hide !
Answer:C
26. The torque developed in the cage induction motor with autostarter is
k/torque with direct switching
K x torque with direct switching
K2 x torque with direct switching
k2/torque with direct switching
Hide !
Answer:C
27. When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered
in series
in parallelin series-parallel
in parallel with stator
Hide !
Answer:B
28. It is advisable to avoid line-starting of induction motor and use starter because
motor takes five to seven times its full load current
it will pick-up very high speed and may go out of step
it will run in reverse direction
starting torque is very high
Hide !
Answer:A
29. Stepless speed control of induction motor is possible by which of the following methods ?
e.m.f. injection in rotor eueuit
Changing the number of poles
Cascade operation
None of the above
Hide !
Answer:B
31. In the circle diagram for induction motor, the diameter of the circle represents
slip
rotor currentrunning torque
line voltage
Hide !
Answer:B
32. For which motor the speed can be controlled from rotor side ?
Squirrel-cage induction motor
Slip-ring induction motor
Both (a) and (b)
None of the above
Hide !
Answer:B
33. If any two phases for an induction motor are interchanged
the motor will run in reverse direction
the motor will run at reduced speed
the motor will not run
the motor will burn
Hide !
Answer:A
34. An induction motor is
self-starting with zero torque
self-starting with high torqueself-starting with low torque
non-self starting
Hide !
Answer:C
35. The maximum torque in an induction motor depends on
frequency
rotor inductive reactance
square of supply voltage
all of the above
Hide !
Answeremoticon_grin
36. In three-phase squirrel-cage induction motors
rotor conductor ends are short-circuited through slip rings
rotor conductors are short-circuited through end rings
rotor conductors are kept open
rotor conductors are connected to insulation
Hide !
Answer:B
37. In a three-phase induction motor, the number of poles in the rotor winding is always
(a) zero
(b) more than the number of poles in stator
(c) less than number of poles in stator(d) equal to number of poles in stator
Hide !
Answeremoticon_grin
38. DOL starting of induction motors is usually restricted to
low horsepower motors
variable speed motors
high horsepower motors
high speed motors
Hide !
Answer:A
39. The speed of a squirrel-cage induction motor can be controlled by all of the following except
changing supply frequency
changing number of poles
changing winding resistance
reducing supply voltage
Hide !
Answer:C
40. The 'crawling" in an induction motor is caused by
high loads
low voltage supplyimproper design of machine
harmonics developed in the motor
Hide !
Answeremoticon_grin
41. The power factor of an induction motor under no-load conditions will be closer to
0.2 lagging
0.2 leading
0.5 leading
unity
Hide !
Answer:A
42. The 'cogging' of an induction motor can be avoided by
proper ventilation
using DOL starter
auto-transformer starter
having number of rotor slots more or less than the number of stator slots (not equal)
Hide !
Answeremoticon_grin
43. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as
humming
huntingcrawling
cogging
Hide !
Answer:C
44. Slip of an induction motor is negative when
magnetic field and rotor rotate in opposite direction
rotor speed is less than the syn-chronous speed of the field and are in the same direction
rotor speed is more than the syn-chronous speed of the field and are in the same direction
none of the above
Hide !
Answer:C
45. Size of a high speed motor as compared to low speed motorfor the same H.P. will be
bigger
smaller
same
any of the above
Hide !
Answer:B
46. A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor
will continue running burning its one phase
will continue running burning its two phaseswill stop and carry heavy current causing permanent damage to its winding
will continue running without any harm to the winding
Hide !
Answer:A
47. A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor
will continue running burning its one phase
will continue running burning its two phase
will stop and carry heavy current causing permanent damage to its winding
will continue running without any harm to the winding
Hide !
Answer:C
48. Low voltage at motor terminals is due to
inadequate motor wiring
porely regulated power supply
any one of the above
none of the above
Hide !
Answer:C
49. In an induction motor the relationship between stator slots and rotor slots is that
stator slots are equal to rotor slots
stator slots are exact multiple of rotor slotsstator slots are not exact multiple of rotor slots
none of the above
Hide !
Answer:C
50. Slip ring motor is recommended where
speed control is required
frequent starting, stopping and reversing is required
high starting torque is needed
all above features are required
Hide !
Answeremoticon_grin
51. As load on an induction motor goes on increasing
its power factor goes on decreasing
its power factor remains constant
its power factor goes on increasing even after full load
its power factor goes on increasing upto full load and then it falls again
Hide !
Answeremoticon_grin
52. If a 3-phase supply is given to the stator and rotor is short circuited rotor will move
in the opposite direction as the direction of the rotating field
in the same direction as the direction of the fieldin any direction depending upon phase squence of supply
Show Answer
53. It is advisable to avoid line starting of induction motor and use starter because
it will run in reverse direction
it will pick up very high speed and may go out of step
motor takes five to seven times its full load current
starting torque is very high
Hide !
Answer:C
54. The speed characteristics of an induction motor closely resemble the speedload characteristics of which of the following machines
D.C. series motor
D.C. shunt motor
universal motor
none of the above
Hide !
Answer:B
55. Which type of bearing is provided in small induction motors to support the rotor shaft
Ball bearings
Cast iron bearings
Bush bearings
None of the aboveHide !
Answer:A
56. A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs.
What will eventually happen ? It will
stall after sometime
stall immediately
continue to run at lower speed without damage
get heated and subsequently get damaged
Hide !
Answeremoticon_grin
57. 5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ?
730 r.p.m.
960 r.p.m.
1440 r.p.m.
2880 r.p.m.
Hide !
Answer:A
58. A 3-phase slip ring motor has
double cage rotor
wound rotor
short-circuited rotorany of the above
Hide !
Answer:B
59. The starting torque of a 3-phase squirrel cage induction motor is
twice the full load torque
1.5 times the full load torque
equal to full load torque
Hide !
Answer:B
60. Short-circuit test on an induction motor cannot be used to determine
windage losses
copper losses
transformation ratio
power scale of circle diagram
Hide !
Answer:A
61. In a three-phase induction motor
iron losses in stator will be negligible as compared to that in rotor
iron losses in motor will be neg¬ligible as compared to that in rotor
iron losses in stator will be less than that in rotor
iron losses in stator will be more than that in rotorHide !
Answeremoticon_grin
62. In case of 3-phase induction motors, plugging means
pulling the motor directly on line without a starter
locking of rotor due to harmonics
starting the motor on load which is more than the rated load
interchanging two supply phases for quick stopping
Hide !
Answeremoticon_grin
63. Which is of the following data is required to draw the circle diagram for an induction motor ?
Block rotor test only
No load test only
Block rotor test and no-load test
Block rotor test, no-load test and stator resistance test
Hide !
Answeremoticon_grin
64. In three-phase induction motors sometimes copper bars are placed deep in the rotor to
improve starting torque
reduce copper losses
improve efficiency
improve power factorHide !
Answer:A
65. In a three-phase induction motor
power factor at starting is high as compared to that while running
power factor at starting is low as compared to that while running
power factor at starting in the same as that while running
Hide !
Answer:B
68. The shape of the torque/slip curve of induction motor is
parabola
hyperbola
rectangular parabola
straight line
Hide !
Answer:C
69. A change of 4% of supply voltage to an induction motor will produce a change of approximately
4% in the rotor torque
8% in the rotor torque
12% in the rotor torque
16% in the rotor torque
Hide !Answeremoticon_grin
70. The stating torque of the slip ring induction motor can be increased by adding
external inductance to the rotor
external resistance to the rotor
external capacitance to the rotor
both resistance and inductance to rotor
Hide !
Answer:B
71. A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles.
The slip of the machine will be
0.01
0.02
0.03
0.04
Hide !
Answeremoticon_grin
73. In the squirrel-cage induction motor the rotor slots are usually given slight skew
to reduce the magnetic hum and locking tendency of the rotor
to increase the tensile strength of the rotor bars
to ensure easy fabrication
none of the aboveHide !
Answer:A
74. The torque of a rotor in an induction motor under running condition is maximum
at the unit value of slip
at the zero value of slip
at the value of the slip which makes rotor reactance per phase equal to the resistance per phase
at the value of the slip which makes the rotor reactance half of the rotor
Hide !
Answer:C
75. What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero ?
The slip of the motor will be 5%
The rotor will not run
The rotor will run at very high speed
The torque produced will be very large
Hide !
Answer:B
78. Lubricant used for ball bearing is usually
graphite
grease
mineral oil
molassesHide !
Answer:B
79. An induction motor can run at synchronous speed when
it is run on load
it is run in reverse direction
it is run on voltage higher than the rated voltage
e.m.f. is injected in the rotor circuit
Hide !
Answer:B
81. The torque developed by a 3-phase induction motor least depends on
rotor current
rotor power factor
rotor e.m.f.
shaft diameter
Hide !
Answer:A
82. In an induction motor if air-gap is increased
the power factor will be low
windage losses will be more
bearing friction will reduce
copper loss will reduce In an induction motorHide !
Answer:A
83. In induction motor, percentage slip depends on
supply frequency
supply voltage
copper losses in motor
none of the above
Hide !
Answer:C
84. When R2 is the rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque
under running conditions will be
sR2X2 = 1
sR2 = X2
R2 = sX2
R2 = s^{2}X2
Hide !
Answer:C
86. The low power factor of induction motor is due to
rotor leakage reactance
stator reactance
the reactive lagging magnetizing current necessary to generate the magnetic fluxall of the above
Hide !
Answeremoticon_grin
87. Insertion of reactance in the rotor circuit
reduces starting torque as well as maximum torque
increases starting torque as well as maximum torque
increases starting torque but maxi-mum torque remains unchanged
increases starting torque but maxi-mum torque decreases
Hide !
Answer:A
88. Insertion of resistance in the rotor of an induction motor to develop a given torque
decreases the rotor current
increases the rotor current
rotor current becomes zero
rotor current remains same
Hide !
Answeremoticon_grin
89. For driving high inertia lood best type of induction motor suggested is
slip ring type
squirrel cage type
any of the abovenone of the above
Hide !
Answer:A
90. Temperature of the stator winding of a three phase induction motor is obtained by
resistance rise method
thermometer method
embedded temperature method
all above methods
Hide !
Answeremoticon_grin
91. The purpose of using short-circuit gear is
to short circuit the rotor at slip rings
to short circuit the starting resistances in the starter
to short circuit the stator phase of motor to form star
none of the above
Hide !
Answer:A
92. In a squirrel cage motor the induced e.m.f. is
dependent on the shaft loading
dependent on the number of slots
slip times the stand still e.m.f. induced in the rotornone of the above
Hide !
Answer:C
93. Less maintenance troubles are experienced in case of
slip ring induction motor
squirrel cage induction motor
both (a) and (b)
none of the above
Hide !
Answer:B
94. A squirrel cage induction motor is not selected when
initial cost is the main consideration
maintenance cost is to be kept low
higher starting torque is the main consideration
all above considerations are involved
Hide !
Ansswer:C
95. Reduced voltage starter can be used with
slip ring motor only but not with squirrel cage induction motor
squirrel cage induction motor only but not with slip ring motor
squirrel cage as well as slip ring induction motornone of the above
Hide !
Answer:C
96. Slip ring motor is preferred over squirrel cage induction motor where
high starting torque is required
load torque is heavy
heavy pull out torque is required
all of the above
Hide !
Answer:A
97. In a star-delta starter of an induction motor
resistance is inserted in the stator
reduced voltage is applied to the stator
resistance is inserted in the rotor
applied voltage per1 stator phase is 57.7% of the line voltage
Hide !
Answeremoticon_grin
98. The torque of an induction motor is
directly proportional to slip
inversely proportional to slip
proportional to the square of the slipnone of the above
Hide !
Answeremoticon_grin
99. The rotor of an induction motor runs at
synchronous speed
below synchronous speed
above synchronous speed
any of the above
Hide !
Answer:B
100. The starting torque of a three phase induction motor can be increased by
increasing slip
increasing current
both (a) and (b)
none of the above
Hide !
Answer:C
101. Insertion of resistance in the stator of an induction motor
increases the load torque
decreases the starting torque
increases the starting torquenone of the above
Hide !
Answer:BEEE Unit-3 Special Purpose Motors MCQ's
Edit
1. A capacitor start single phase induction motor will usually have a power factor of
(A) unity
(B) 0.8 leading
(C) 0.6 leading
(D) 0.6 lagging.
Hide !
Ans D
Show Answer
2. A capacitor start, capacitor run single phase induction motor is basically a
(A) ac series motor
(B) dc series motor
(C) 2 phase induction motor
(D) 3 phase induction motor.
Hide !
Ans C
Show Answer
3. The starting torque of a capacitor start motor is
(A) zero
(B) low
(C) same as rated torque
(D) more than rated torque.Hide !
Ans B
Show Answer
4. The torque developed by a split phase motor is proportional to
(A) Sine of angle between lm and ls
(B) Cosine of angle between lm and Is
(C) Main winding current, Im
(D) Auxiliary winding current,Is
Hide !
Ans A
Show Answer
5. A capacitor start single phase induction motor is switched on the supply with its capacitor replaced by an inductor of equivalent reactance value. It will
(A) not start
(B) start and run
(C) start and then stall
(D) none of the above.
Hide !
Ans A
Show Answer
6. The starting capacitor of a single phase motor is
(A) Electrolytic capacitor(B) Ceramic capacitor
(C) Paper capacitor
(D) None of the above.
Hide !
Ans A
Show Answer
7. Which of the following is the most economical method of starting a single phase motor ?
(A) Resistance start method
(B) Inductance start method
(C) Capacitance start method
(D) Split-phase method.
Hide !
Ans C
Show Answer
8. The number of turns in the starting winding of a capacitor start motor as compared to that for split phase motor is
(A) same
(B) more
(C) less
(D) none of the above.
Hide !
Ans B
9. In a split phase motor, the ratio of number of turns for starting winding to that for running winding is
(A) 2.0(B) more than 1
(C) 1.0
(D) less than 1.
Hide !
Ans D
Show Answer
10. A single phase motor generally used for small air compressor is
(A) capacitor start capacitor run motor
(B) reluctance motor
(C) universal motor
(D) shaded pole motor.
Hide !
Ans A
Show Answer
Out of the following motors, which will give the highest starting torque ?
(A) Universal motor
(B) Capacitor start motor
(C) Shaded pole motor
(D) All have zero starting torque.
Hide !
Ans B
Show Answer12. Which single phase ac motor will you select for record players and tape recorders ?
(A) Hysteresis motor
(B) Shaded pole motor
(C) Reluctance motor
(D) Two value capacitor motor.
Hide !
Ans A
Show Answer
13. A universal motor is one
(A) which can run on any value of supply voltage
(B) which has infinitely varying speed
(C) which can operate on ac as well as dc voltage
(D) which can work as single phase or three phase motor.
Hide !
Ans C
Show Answer
14. Under normal operating conditions which motor can run at 5000 rpm ?
(A) Synchronous motor
(B) Induction motor
(C) Universal motor
(D) No motor can give 5000 rpm.
Hide !Ans C
Show Answer
15. The motor used in household refrigerators is
(A) dc series motor
(B) dc shunt motor
(C) universal motor
(D) single phase induction motor.
Hide !
Ans D
Show Answer
16. Single phase motors are commercially manufactured up to
(A) 1H.P.
(B) 2 H.P.
(C) 5 H.P.
(D) 10 H.P.
Hide !
Ans B
17. The direction of rotation of universal motor can be reversed by
(A) reversing the supply terminals
(B) switching over from ac to dc
(C) interchanging the brush leads
(D) any of the above.Hide !
Ans C
18. A universal motor operates on
(A) constant speed and varying load
(B) constant load and varying speed
(C) approximately constant speed and load
(D) synchronous speed with varying load.
Hide !
Ans C
19. Which of the following single phase motors will operate at high power factor ?
(A) shaded pole motor
(B) capacitor run motor
(C) split phase motor
(D) capacitor start motor.
Hide !
Ans B
20. A motor suitable for signaling device is
(A) induction motor
(B) dc shunt motor
(C) dc series motor
(D) reluctance motors.
Hide !
Ans D
21. Which capacitor is preferred in case of single phase motor(A) Paper capacitor
(B) Ceramic capacitor
(C) Mica capacitor
(D) Electrolytic capacitor.
Hide !
Ans D
22. The motor used for driving the record player deck is
(A) dc series motor
(B) synchronous motor
(C) hysteresis motor
(D) dc shunt motor.
Hide !
Ans C
23. When a motor speed of 5000 rpm is required, which motor will you select ?
(A) Capacitor start motor
(B) Shaded pole motor
(C) Hysteresis motor
(D) Universal motor.
Hide !
Ans D
24. As compared to other single phase ac motors a universal motor has
(A) speed ratio of 2: 1 on ac/dc
(B) highest efficiency on 50 Hz supply
(C) high horse power/kg ratio(D) all of the above.
Hide !
Ans C
25. When a universal motor is operated on no load, its speed is limited by
(A) armature reaction
(B) armature weight
(C) windage and friction
(D) supply voltage frequency.
Hide !
Ans C
26. Which of the following applications make use of a universal motor ?
(A) Floor polishing machine
(B) Oil expeller
(C) Portable tools
(D) Lathe machines.
Hide !
Ans C
27. In portable tools the speed of the driven shaft is reduced by
(A) Gearing
(B) Belt drive
(C) Chain drive
(D) Fluid coupling.Hide !
Ans A
28. For ceiling fans generally the single phase motor used is
(A) split phase type
(B) capacitor start type
(C) capacitor start and run type
(D) permanent capacitor type.
Hide !
Ans D
29. In case of split phase motors the phase shift is usually limited to
(A) 3 degrees
(B) 60 degrees
(C) 90 degrees
(D) 150 degrees.
Hide !
Ans A
30. The capacitance of a small single phase motor will be of the order of
(A) Kilo farads
(B) Few hundred farads
(C) Farads
(D) Micro or pico farads.
Hide !
Ans D31. The type of starting relay used on single phase hermetic motor is
(A) hot wire relay
(B) timing relay
(C) current coil relay
(D) voltage coil relay
(E) any of the above.
Hide !
Ans C
32. Reluctance motors are
(A) doubly excited
(B) singly excited
(C) either doubly excited or singly excited
(D) none of the above.
Hide !
Ans B
Show Answer
Show Answer
Show Answer
33. Electric motors are generally designed to have maximum efficiency at
(A) full load
(B) near full load
(C) half load(D) near half load.
Hide !
Ans B
34. Which of the following is non-reversible motor ?
(A) Universal motor
(B) Capacitor start split phase motor
(C) Resistance start split phase motor
(D) Permanent split capacitor motor.
Hide !
Ans C
35. Which motor is generally used for electric shavers ?
(A) Shaded pole motor
(B) Hysteresis motor
(C) Reluctance motor
(D) Universal motor.
Hide !
Ans D
36. The motor useful for signaling and timing device is
(A) Reluctance motor
(B) Shaded pole motor
(C) Hysteresis motor
(D) Two value capacitor motor.Hide !
Ans A
37. A motor generally used in toys is
(A) Hysteresis motor
(B) Shaded pole motor
(C) Two value capacitor motor
(D) Reluctance motor.
Hide !
Ans B
38. Single phase motors generally get over heated due to
(A) Overloading
(B) Short windings
(C) Bearing troubles
(D) Any of the above.
Hide !
Ans D
39. Which of the following is a reversible motor ?
(A) Universal motor
(B) Capacitor start split phase motor
(C) Both (A) and (B) above
(D) None of the above.
Hide !
Ans D40. The starting torque of a single phase induction motor is
(A) uniform
(B) high
(C) low
(D) zero.
Hide !
Ans D
41. Which of the following motors will operate at high power factor ?
(A) Universal motor
(B) Capacitor start motor
(C) Capacitor run motor
(D) Split phase motor.
Hide !
Ans C
42. Which of the following statements about reluctance motor is not true ?
(A) It is self starting
(B) It runs at constant speed
(C) It needs no dc excitation for its rotor
(D) It can operate on ac as well as dc.
Hide !
Ans D
43. The rotor for a hysteresis motor
(A) is made of chrome steel
(B) has high retentivity(C) has high hysteresis loss
(D) should have all above properties.
Hide !
Ans D
Show Answer
Show Answer
Show Answer
44. The speed of a universal motor can be controlled by
(A) introducing a variable resistance in series with the motor
(B) tapping the field at various points
(C) centrifugal mechanisms
(D) any of the above.
Hide !
Ans D
45. What could be the smallest size of a universal motor?
(A)1/10 HP
(B)1/20 HP
(C)1/20 HP
(D)1/2000 HP.
Hide !
Ans C46. The short coming of repulsion motor is
(A) variation of speed with load
(B) low power factor
(C) tendency to spark at brushes
(D) all of the above.
Hide !
Ans D
47. The disadvantage of shaded pole motor is
(A) low starting torque'
(B) low efficiency
(C) very little over load capacity
(D) all of the above.
Hide !
Ans D
Show Answer
Show Answer
Show Answer
48. The efficiency of shaded pole motor is in the range
(A) 80 to 95 percent
(B) 70 to 80 percent
(C) 50 to 70 percent
(D) 5 to 35 percent.Hide !
Ans D
Show Answer
Show Answer
Show Answer
49. For domestic sewing machine the size of the motor required will be
(A) 10-15 watts
(B) 15-25 watts
(C) 100-150 watts
(D) 250 to 750 watts.
Hide !
Ans C
Show Answer
Show Answer
Show Answer
50. A ceiling fan of 1400 mm sweep will have motor rating of
(A) 10 to 15 watts(B) 50 to 70 watts
(C) 120 to 180 watts
(D) 250 to 500 watts.
Hide !
Ans C
51. Which of the following applications would need the smallest size of motor ?
(A) Domestic motor
(B) Electric clock
(C) Table fan
(D) Sewing machine.
Hide !
Ans B
52. All single phase ac motors are designed to operate usually on
(A) 220 V only
(B)220V + 10V
(C) 220 ± 0 V
(D) 220 ± 10% volts.
Hide !
Ans D
53. All single phase ac motors are designed usually to operate on the frequency
(A) 50 Hz
(B) 50 ± 0.5 Hz
(C) 50 ±1 Hz
(D) 50. ± 5 Hz.Hide !
Ans D
54. When a dc series motor is connected to ac supply, it will
(A) spark excessively
(B) give poor efficiency
(C) run on poor power factor
(D) all of the above.
Hide !
Ans D
55. The torque-speed characteristic of a repulsion motor resembles that of which of the following dc motor ?
(A) separately excited motor
(B) shunt motor
(C) series is motor
(D) compound motor.
Hide !
Ans D
56. In a single phase capacitor motor the direction of rotation will be in the opposite direction to the original when
(A) electrolytic capacitor is replaced by paper capacitor
(B) two capacitors of equal value are used
(C) capacitor is replaced by a resistance
(D) capacitor is replaced by an inductor.
Hide !Ans D
57. In a hysteresis motor, the position of shaded pole with respect to main pole determines
(A) speed of motor
(B) direction of rotation
(C) hysteresis loss
(D) no load rpm.
Hide !
Ans B
58. In a shaded pole motor, the direction of rotation is from
(A) main pole to shaded pole
(B) shaded pole to main pole
(C) depends on supply line polarity.
Hide !
Ans A
59. Which motor is generally used in tape recorders ?
(A) Universal motor
(B) Reluctance motor
(C) Split phase motor
(D) Hysteresis motor.
Hide !
Ans D60. In a shaded pole motor, shading coils are used to
(A) reduce windage losses
(B) reduce friction losses
(C) produce rotating magnetic field
(D) to protect against sparking.
Hide !
Ans C
61. In a shaded pole motor, the locked rotor current is
(A) 10 times the full load current
(B) 4 to 5 times the full load current
(C) slightly more than the full load current
(D) less than the full load current.
Hide !
Ans C
62. Shaded pole motors are not provided with
(A) capacitor
(B) centrifugal switch
(C) commutator
(D) all of the above.
Hide !
Ans D63. In a universal motor, normally the ratio of width of brush to the width of commutator segments is
(A) 1 : 1
(B) 1: 2
(C) 2 : 1
(D) 4:1.
Hide !
Ans C
64. For a given output and speed, a universal motor as compared to 220 V, 50 Hz supply will require
(A) less voltage at low frequency
(B) less voltage at high frequency
(C) high voltage at high frequency
(D) high voltage at low frequency.
Hide !
Ans A
65. Which figure represents a shaded pole motor ?
(A) figure A
(B) figure B
(C) figure C
(D) figure D.
Hide !
Ans DQuestions 65 to 69 refer to the Figure given below. Single phase configurations are shown in the Figure.
66. Which figure represents a capacitor start motor ?
(A) figure A
(B) figure B
(C) figure C
(D) none of the figures.
Hide !
Ans D
67. Which figure represents a universal motor ?
(A) figure A
(B) figure B
(C) figure C
(D) none of the figures.
Hide !
Ans B
68. Figure A represents
(A) capacitor start capacitor run motor
(B) Hysteresis motor
(C) AC series motor
(D) Repulsion motor.
Hide !Ans C
69. A hysteresis motor is represented by
(A) figure A
(B) figure B
(C) figure C
(D) none of the figures.
Hide !
Ans C
70. A capacitor motor of 1/4 HP needs a condenser of 8 μ F. A similar motor of 3/4 HP will need a condenser of
(A) 20 μF
(B) 8 μF
(C) 2 μF.
Hide !
Ans A
Show Answer
Show Answer
Show Answer
71. The rotor of which motor does not have winding on it ?(A) Universal motor
(B) Hysteresis motor
(C) Reluctance motor
(D) Repulsion motor.
Hide !
Ans B
Show Answer
Show Answer
Show Answer
72. Which motor has unsymmetrical rotor ?
(A) Universal motor
(B) Shaded pole motor
(C) Split-phase motor
(D) Reluctance motor.
Hide !
Ans D
73. If a single phase motor runs slow, the probable case may be
(A) overload
(B) low frequency
(C) low voltage(D) any of the above.
Hide !
Ans D
74. A single phase capacitor start motor will take starting current nearly
(A) same as full load current
(B) twice the full load current
(C) three times the full load current
(D) four the six times the full load current.
Hide !
Ans B
75. Which motor will make least noise ?
(A) Capacitor motor
(B) Universal motor
(C) Shaded pole motor
(D) Hysteresis motor.
Hide !
Ans D
76. If a single phase motor runs hot the probable cause cannot be
(A) high voltage
(B) shorted stator coils
(C) blown fuses
(D) low voltage.Hide !
Ans C
77. A single phase capacitor run motor will have starting torque as
(A) 1/2 of full load torque
(B) same as full load torque
(C) 1 1/2 times full load torque
(D) 2 times full load torque.
Hide !
Ans C
78. Which of the following single phase motors will be cheapest ?
(A) Capacitor start motor
(B) Capacitor run motor
(C) Reluctance motor
(D) All have same cost.
Hide !
Ans A
79. Noise in an electric motor may be due to
(A) cooling air
(B) magnetic effects
(C) bearings
(D) all of the above.
Hide !Ans D
80. For a system involving sound recording and reproduction which motor would you select ?
(A) Hysteresis motor
(B) Universal motor
(C) Shaded pole motor
(D) Reluctance motor.
Hide !
Ans A
81. Cranes and hoists offer which type of load ?
(A) non-reversing, no load start
(B) reversing, no load start
(C) reversing,heavy start
(D) non-reversing, heavy start.
Hide !
Ans C
82. If a single phase motor runs hot, the probable cause may be
(A) overload
(B) low voltage
(C) high voltage
(D) any of the above.
Hide !
Ans D83. Which motor is relatively free from mechanical and magnetic vibrations?
(A) Reluctance motor
(B) Hysteresis motor
(C) Universal motor
(D) Shaded pole motor.
Hide !
Ans B
Questions 84 to 88 refer to the figure given below :
84. The figure shows the torque speed characteristics of a universal motor. Which curve is likely to represent the variation of power factor ?
(A) curve A
(B) curve B
(C) curve C
(D) curve D.
Hide !
Ans A
85. Which curve represents the variation of speed with torque for the motor ?
(A) curve A
(B) curve B
(C) curve C
(D) curve D.
Hide !
Ans D
86. Curve C is likely to represent(A) armature current
(B) iron losses
(C) efficiency
(D) windage losses.
Hide !
Ans C
87. If curve C represents efficiency while the motor is operating on ac supply, curve B is likely to represent
(A) peak value of supply
(B) core losses
(C) line voltage
(D) efficiency on dc supply.
Hide !
Ans D
88. Reluctance motors are
(A) doubly excited
(B) singly excited
(C) multiply excited
(D) unexcited.
Hide !
Ans B
89. Which of the following motors does not have constant speed characteristics ?
(A) Reluctance motor
(B) Hysteresis motor
(C) Universal motor(D) All of the above.
Hide !
Ans C
90. For the same rating which motor has the highest starting torque ?
(A) Universal motor
(B) Split phase motor
(C) Synchronous motor
(D) All have identical starting torque.
Hide !
Ans A
91. A capacitor selected for capacitor-run motor should be rated for
(A) peak voltage
(B) rms voltage
(C) average voltage.
Hide !
Ans A
92. If a single phase motor fails to start, the probable cause may be
(A) open in auxiliary winding
(B) open in main winding
(C) blown fuses
(D) any of the above.
Hide !
Ans D93. For torque-speed curves shown, which curve represents the characteristics of a repulsion start induction run motor ?
(A) curve A
(B) curve B
(C) curve C
(D) curve D.
Hide !
Ans D
94. Which curve represents the characteristics of a single phase capacitor start motor ?
(A) curve A
(B) curve B
(C) curve C
(D) curve D.
Hide !
Ans B
95. The reluctance torque in a motor is present when the reluctance seen by
(A) rotor mmf varies
(B) rotor mmf remains constant
(C) stator mmf is constant.
Hide !
Ans A
96. Which time-phasor diagram is valid for split single phase motor ?(A) A
(B) B
(C) C
(D) None.
Hide !
Ans A
97. The phasor diagram [figure (B) of Question 96] is valid for
(A) Shaded pole motor
(B) Capacitor start motor
(C) Split phase motor
(D) Universal motor.
Hide !
Ans B
98. Which single phase motor has relatively high power factor ?
(A) Universal motor
(B) Split phase motor
(C) Repulsion motor
(D) Synchronous motor.
Hide !
Ans A
99. Which motor would you select for vacuum cleaners ?
(A) Universal motor(B) Repulsion motor
(C) Hysteresis motor
(D) Reluctance motor.
Hide !
Ans A
100. If torque speed characteristics of a motor is represented by the figure below the motor is likely to be
(A) Shaded pole motor
(B) Repulsion motor
(C) AC/DC motor
(D) Capacitance start capacitance, run motor.
Hide !
Ans C
101. If the ceiling fan, when switched on, runs at slow speed in the reverse direction, it can be concluded that
(A) winding has burnt out
(B) bearings are worn out
(C) capacitor is ineffective
(D) none of the above.
Hide !
Ans C
102. For how many poles is a split-phase motor wound if it operates at 1750 rpm at full load from a 60 Hz source ?
(A) 2 poles(B) 4 poles
(C) 6 poles
(D) 12 poles.
Hide !
Ans B
103. Which of the following capacitor-start split phase motor will have the largest value of capacitance ?
(A)1/8 HP, 3450 rpm
(B) 1/4 HP, 1725 rpm
(C) 1/2 HP, 1140 rpm
(D) 3/4 HP, 1140 rpm.
Hide !
Ans D
104. The speed of a split phase induction motor can be reversed by reversing the leads of
(A) auxiliary winding
(B) main winding
(C) either of (A) and (B) above
(D) speed cannot be reversed.
Hide !
Ans C
105. A capacitor start type single phase induction motor has its capacitor replaced by an inductor of equivalent reluctance value. If the motor is now switched on to
the supply, it will
(A) run in the reverse direction
(B) not run
(C) run with more noise and low torque(D) start but not take the load.
Hide !
Ans B
106. In ac series motor the purpose of providing compensating winding is to
(A) reduce sparking at brushes
(B) increase the torque
(C) reduce heating of armature
(D) minimize vibrations.
Hide !
Ans A
107. The approximate value of capacitance to be used on 50 Hz, capacitor start split phase 1725 rpm motor will be
(A) 10 micro F
(B) 100 micro F
(C) 350 micro F
(D) 700 micro F.
Hide !
Ans C
108. Which of the following is used on single phase hermetic motors ?
(A) Voltage coil
(B) Hot wire
(C) Current coil
(D) All of the above.
Hide !Ans A
109. Normally, the auxiliary winding in a single phase induction motor is cut off when the motor reaches a certain speed except in case of
(A) shaded pole motor
(B) capacitor start motor
(C) capacitor start, capacitor run motor
(D) split phase motor.
Hide !
Ans C
110. In case of a reluctance motor, when the. load is increased so that it cannot maintain synchronous speed the motor will
(A) fall out of synchronism and come to stand still
(B) run as induction motor
(C) become unstable
(D) draw excessive armature current and may burn out.
Hide !
Ans B
111. Most important characteristics of a single phase motor is
(A) that it requires only one winding
(B) that it is not self-starting
(C) that it is self-starting
(D) all of the above.
Hide !
Ans B
112. In a capacitor start induction motor, the stalling torque is directly related to angle a between the 2 winding currents by(A) tan α
(B) cot α
(C) sin α
(D) secα.
Hide !
Ans C
113. In a capacitor start motor, the capacitor is connected in series with
(A) starting winding
(B) running winding
(C) compensating winding
(D) none of the above.
Hide !
Ans A
114. The capacitor used for running purpose in a two-capacitor motor is
(A) Air capacitor
(B) Ceramic capacitor
(C) Paper spaced oil-filled type
(D) None of the above.
Hide !
Ans C
115. In split phase motor,
(A) main winding has low resistance and high resistance
(B) main winding has high resistance and high reactance
(C) main winding has low resistance and low reactance(D) None of the above.
Hide !
Ans A
116. A single phase motor has
(A) Zero starling torque
(B) Low starting torque
(C) High starting torque
(D) None of above.
Hide !
Ans A
117. In a single phase motor, phase splitting can be done
(A) with an auxiliary winding of high resistance
(B) with an auxiliary winding of high reactance
(C) with an auxiliary winding in series with a capacitor
(D) by any of the above three methods.
Hide !
Ans D
118. A single phase self-starting motor has two stator windings
(A) which are placed at 900 and fed in phase
(B) which are placed at 900 and fed out of phase
(C) which are placed at 450 and fed out of phase
(D) none of above.
Hide !Ans B
119. In a single phase hysteresis motor, starting torque is caused by
(A) Eddy current
(B) Hysteresis
(C) Both eddy current and hysteresis
(D) None of the above.
Hide !
Ans A
120. A two value capacitor motor when compared to a capacitor start has
(A) Higher starting torque and higher running power factor
(B) Higher starting torque and lower running power factor
(C) Same starting torque and improved running power factor
(D) None of the above.
Hide !
Ans C
121. Single phase induction motor can be made self starting by
(A) adding series combination of a capacitor and auxiliary winding in parallel with the main winding
(B) adding an auxiliary winding in parallel with the main winding
(C) adding an auxiliary winding in series with a capacitor and the main winding.
Hide !
Ans A
122. The following motor is popularly used in driving a refrigerator
(A) d.c. shunt motor
(B) universal motor(C) plain cage induction motor
(D) squirrel cage induction motor.
Hide !
Ans B
123. Motor used in driving a tape recorder is
(A) Hysteresis motor
(B) Synchronous motor
(C) Induction motor
(D) Universal motor.
Hide !
Ans A
124. Speed of a repulsion motor at no load is
(A) low
(B) very low
(C) high
(D) dangerously high.
Hide !
Ans D
125. Operation of a hysteresis motor can be explained on the basis of
(A) cross field theory
(B) continuously revolving magnetic flux
(C) pulsating magnetic flux
(D) intermittently revolving magnetic flux.Hide !
Ans D
126. The main drawback of a shaded pole motor is
(A) Low efficiency
(B) Low starting torque
(C) Very little overload capacity
(D) All of these.
Hide !
Ans D
127. Consider the following single-phase motors :
I. Capacitor start motor
II. Capacitor start and run motor
III. Permanent split capacitor motor
IV. Shaded pole motor.
The correct sequence of the increasing order of their costs is
(A) IV, III, II, I
(B) IV, III, I, II
(C) III, IV, II, I
(D) 111, IV, I, II.
Hide !
Ans A
128. A universal motor runs at
(A) higher speed with dc supply and with less sparking
(B) higher speed with ac supply and with less sparking
(C) same speed with both ac and dc supplies(D) higher speed with ac supply but with increased sparking at the brushes.
Hide !
Ans C
129. The main reason of using a hysteresis motor , for high quality tape recorders and record players is that
(A) its speed is constant (synchronous)
(B) it develops extremely steady torque
(C) it requires no centrifugal switch
(D) its operation is not affected by mechanical vibrations.
Hide !
Ans A
130. A fluctuating voltage supply is detrimental to a refrigerator motor, but not to a ceiling fan motor, although both are single-phase induction motors because, the
refrigerator motor
(A) is made more robust than the fan motor
(B) is subjected to short duty cycle but the fan motor is subjected to continuous duty
(C) is enclosed in a sealed unit while the fan motor is open to the environment
(D) load is constant, but the fan motor load is voltage dependent.
Hide !
Ans CEEE Unit-4 Introduction to Microcontrollers MCQ's Part-A
Edit
QUESTION
Which of the following is an open- source embedded platform?
A Legato
B Arduino
C Teagueduino
D All of the above
Hide !
Answer D
QUESTION
Atmega 328P is a _____ bit microconrroller
A 8
B 4
C 16
D 64
Hide !
Answer A
QUESTION
Atmega 328P is based on which architechture?A RISC
B CISC
C Von neumann
D None of above
Hide !
Answer A
QUESTION
Which of the following is not found in the bit pattern of a status register?
A Global interrupt enable
B Positive flag
C Negative flag
D Carry flag
Hide !
Answer B
QUESTION
Proximity sensors are used to measure______
A Light
B Sound
C Ultrasonic waves
D Distance
Hide !
Answer DQUESTION
Which of the following can be classified as an actuators?
A Solenoid
B Hydraulic cylinders
C Pneumatic cyliders
D All of above
Hide !
Answer D
QUESTION
Which of the following is not an element of a Data Acquisition system?
A Transducers
B Multiplexers
C Demultiplexers
D Attenuators
Hide !
Answer C
QUESTION
Which of the following is a feature of Arduino?
A Cheaper hardware
B Open source hardware
C Supports multiple operating systems
D All of aboveHide !
Answer D
QUESTION
Operating voltage for Arduino Uno is ____V
A 1.3
B 10
C 5
D 2.8
Hide !
Answer C
QUESTION
Programs written using Arduino IDE are called_____
A Sketches
B Source code
C Codes
D Layouts
Hide !
Answer A
QUESTION
File format for Arduino IDE programs is__________
A .unoB .skt
C .hex
D .ino
Hide !
Answer D
QUESTION
Arduino IDE programs are stored in __________
A Folders
B Root directory
C Sketches
D Sketch book
Hide !
Answer D
QUESTION
The position of declaration of a variable decides its________
A Value
B Usefulness
C Scope
D Type
Hide !
Answer CQUESTION
Which of the following is NOT a type of variable?
A Double
B Long
C Int
D Unsigned float
Hide !
Answer D
QUESTION
Boolean operator for ‘not’ is ______
A ║
B &
C !!
D !
Hide !
Answer D
QUESTION
A microprocessor is a _____________ digital circuit
A Combinational
B Sequential
C Either
D None of aboveHide !
Answer B
QUESTION
Instructions are coded in ____
A Hexadecimal
B Decimal
C Binary
D None of above
Hide !
Answer C
QUESTION
Accumulator is used to_____
A Store data
B Store result
C Both
D None of above
Hide !
Answer C
QUESTION
Status register is also called _________ register
A Pointer
B FlagC A
D Stack
Hide !
Answer B
QUESTION
Access time for memory and I/O devices is more in the case of a __________
A Microprocessor
B Microcontroller
C Both
D None of above
Hide !
Answer A
QUESTION
Atmega 328P has________general purpose working registers
A 16
B 32
C 64
D 128
Hide !
Answer B
QUESTIONAn instruction register holds the ______ instruction
A Current
B Previous
C Next
D All of above
Hide !
Answer A
QUESTION
If DDxn is written as 1, Pxn is configured as _____ pin and if DDxn is written as 0, Pxn is
A Output, Input
B Output, Output
C Input, Input
D Input, Output
Hide !
Answer A
QUESTION
Accuracy and precision of A/D convertors is dependent on _____
A Sampling interval
B Accuracy of system
C Both
D None of above
Hide !
configured as ______ pin.Answer C
QUESTION
Variables should necessary be initialized when declared
A True
B False
C Can’t say
D None of above
Hide !
Answer B
QUESTION
Which of the following registers are present in a microcontroller?
A Status register
B Accumulator
C Instruction register
D All of the above
Hide !
Answer D
QUESTION
Instruction read from memory is loaded into_______
A Instruction register
B Program counter
C StatusD RAM
Hide !
Answer A
QUESTION
The decoded signals are sent as an input to___________
A ALU
B Instruction register
C Control unit
D Status register
Hide !
Answer C
QUESTION
ALU performs the following operation
A Add
B Ex-or
C Shift right
D All of above
Hide !
Answer D
QUESTION
The __________ is responsible for working of all other parts of microcontroller togetherA Control
B ALU
C Accumulator
D Program counter
Hide !
Answer A
QUESTION
_______is used to improve the performance of a microcomputer system
A ROM
B RAM
C Decoders
D Interrupts
Hide !
Answer D
QUESTION
Microcontrollers have ____bit handling instructions
A 2
B 4
C 8
D Multiple
Hide !
Answer DQUESTION
Microcontrollers have ______ number of multi-functioned pins as compared to microprocessors
A More
B Less
C Same
D None of above
Hide !
Answer A
QUESTION
Embedded microcontrollers require________
A Power
B Reset
C Clock
D All of above
Hide !
Answer D
QUESTION
Which is a criteria for selecting a microcontroller?
A Faster speed
B Reliability
C Both
D None of aboveHide !
Answer C
QUESTION
Atmega 328P has ______ general purpose I/O lines for connecting external device
A 15
B 20
C 23
D 24
Hide !
Answer C
QUESTION
The ALU operations are divided into three main categories
A arithmetic,
B logical
C bit-functions
D All of the above
Hide !
Answer D
QUESTION
What will happen in that condition, if an interrupt occurs while the micro controller is
serving any other interrupt?A both the interrupts will be handled simultaneously
B the interrupt which is being done first will be served first
C the interrupt that is more priority in the interrupt vector table will be served first
D the interrupt having low priority in the interrupt vector table will be served first
Hide !
Answer C
QUESTION
Each port pin consists of register bits
A DDxn
B PORTxn
C PINxn
D All of the above
Hide !
Answer D
QUESTION
Instruction CBI PORTB.1 means
A clearing the PORTB register
B clearing the first bit of the PORTB register
C setting the PORTB register
D setting the first bit of the PORTB register
Hide !
Answer BQUESTION
On reset, DDR register of all porths are set to
A 0
B 1
C None of the mentioned
D Both of the mentioned
Hide !
Answer A
QUESTION
Which of the following statements are correct?
A PIN register of a port is used to bring data into CPU from pins
B PORT register is used to send data out to pins
C DDR register is used to control the direction of a port
D all of the mentioned
Hide !
Answer D
QUESTION
Microcontrollers often have
A CPU
B RAM
C ROM
D All of theseHide !
Answer D
QUESTION
Sketches are written in
A Text console
B Text editor
C Both
D None of above
Hide !
Answer B
QUESTION
Which function configures the specified pins to behave either as an input or an output.
A digitalWrite
B digitalRead
C pinMode
D All of above
Hide !
Answer C
QUESTION
Serial ports are controlled by a special chip called as
A UARTB USART
C Both
D None of above
Hide !
Answer A
QUESTION
Serial communication is classified into
A Simplex communication
B Half duplex communication
C Full duplex communication
D All of above
Hide !
Answer D
QUESTION
______ is the most widely used serial I/O interfacing standard
A MAX232
B RS232
C Both
D None of above
Hide !
Answer BQUESTION
In RS232, a logic one (1) is represented by
A 5V
B +3 to +25V
C -3 to -25V
D 0V
Hide !
Answer C
QUESTION
In RS232, a logic one (0) is represented by
A 5V
B +3 to +25V
C -3 to -25V
D 0V
Hide !
Answer B
QUESTION
______ of the 32 registers can be used as three 16-bit indirect address register
A 8
B 6
C 3
D 2Hide !
Answer B
QUESTION
During interrupts and subroutine calls, the return address Program Counter (PC) is stored on the
A SRAM
B STACK
C EEPROM
D None of above
Hide !
Answer B
QUESTION
The Status Register is updated
A After all ALU operations
B Before all ALU operations
C Both
D None
Hide !
Answer A
QUESTION
_______bit in status register must be set for the interrupts to be enabled
A T
B HC S
D I
Hide !
Answer D
QUESTION
The ports are______________
A unidirectional I/O ports with optional internal pull-ups.
B bi-directional I/O ports with optional external pull-ups.
C bi-directional I/O ports with optional internal pull-ups.
D None of the above
Hide !
Answer C
QUESTION
The Timer/Counter can be clocked by an_______
A Internal clock
B External clock
C Internal and External clock
D None of above
Hide !
Answer C
QUESTIONA small portion of the ______is set aside for the general purpose registers used by the processor and also for the input/output and peripheral
subsystems of microcontroller.
A SRAM
B FLASH EEPROM
C EEPROM
D ALL OF ABOVE
Hide !
Answer A
QUESTION
Arduino uno has 14 number of _______pins.
A Analog input pins
B Digital I/O pins
C PWM pins
D None of the above
Hide !
Answer B
QUESTION
Arduino uno has 6 number of _______pins.
A Analog input pins
B Digital I/O pins
C PWM pins
D None of the aboveHide !
Answer A
QUESTION
Which of the following is not found in the bit pattern of a status register?
A Parity flag
B Global interrupt enable
C Negative flag
D Carry flag
Hide !
Answer A
QUESTION
Which is criteria for selecting a microcontroller?
A Faster Speed
B Reliability
C Both
D None
Hide !
Answer C
QUESTION
Microcontroller can be found in ____________
A Data acquisition systems
B PrintersC Modems
D ALL
Hide !
Answer D
QUESTION
A ____________ is a computer system with dedicated function within a larger mechanical or electrical system.
A Microprocessor
B Microcontroller
C Embedded System
D None
Hide !
Answer C
QUESTION
The role of Embedded system is to __________
A Monitor
B Control a Process
C Integrate
D None of These
Hide !
Answer B
QUESTIONA _________________ is an open source embedded platform which can be used for IOT device.
A Legato
B Arduino
C Teagueduino
D Raspberry
Hide !
Answer D
QUESTION
Raspberry Pi is a ___________ platform.
A Private
B Open source
C Closed
D Public
Hide !
Answer B
QUESTION
Atmega 328P performs powerful instructions in __________Cycles.
A 2
B 4
C 16
D 1
Hide !Answer D
QUESTION
Atmega 328P has __________ number of instructions
A 130
B 131
C 132
D 133
Hide !
Answer B
QUESTION
Atmega 328P has _____flash memory.
A 8 KByte
B 4 KByte
C 64KByte
D 32 Kbyte
Hide !
Answer D
QUESTION
Atmega 328P has ___________EPROM.
A 2K
B 4K
C 8KD 1K
Hide !
Answer D
QUESTION
Atmega 328P has __________SRAM.
A 1K
B 2K
C 4K
D 8K
Hide !
Answer B
QUESTION
Atmega 328P has 2 __________bit counters with Prescalar.
A 4
B 8
C 16
D 64
Hide !
Answer B
QUESTION
Atmega 328 P has 1 Timer/Counter with CCM and Prescaler. It is of _______ bits.A 2
B 4
C 8
D 16
Hide !
Answer D
QUESTION
Atmega 328P has a channel _______________ bit ADC.
A 2
B 5
C 10
D 15
Hide !
Answer C
QUESTION
Atmega 328 P consists of __________Serial USART.
A 1
B 2
C 3
D 4
Hide !
Answer AQUESTION
Atmega 328P has special features like __________
A Power-on reset
B Brown-out detection
C Internal Oscillator
D All of These
Hide !
Answer D
QUESTION
How many types of sleep modes does Atmega 328P have?
A 3
B 6
C 9
D 12
Hide !
Answer B
QUESTION
To improve parallelism, __________type of architecture is used.
A Harvard
B Von neuman
C Both
D NoneHide !
Answer A
QUESTION
Atmega 328P has ________levels of pipelining.
A 1
B 2
C 3
D 4
Hide !
Answer A
QUESTION
Access time for Atmega 328P microcontroller is __________clock cycle.
A Single
B Double
C Multiple
D None
Hide !
Answer A
QUESTION
The output of ALU Operations is stored in _____________.
A Program counterB ALU
C Register File
D None
Hide !
Answer C
QUESTION
After every arithmetic operation, _________is updated.
A Status register
B Instruction register
C ALU
D None
Hide !
Answer A
QUESTION
Program counter is __________bits wide.
A 12
B 13
C 14
D 15
Hide !
Answer CQUESTION
Program counter is also called ___________.
A Pointer
B Instruction Pointer
C Address Pointer
D None
Hide !
Answer B
QUESTION
The ________is the circuit that decodes an opcode
A Decoder
B Instruction decoder
C Both
D None
Hide !
Answer B
QUESTION
The I-bit can be set and cleared by application with _________instructions.
A SEI
B CLI
C Both
D NoneHide !
Answer C
QUESTION
The bit copy instruction and bit store instruction use ___________as source or destination.
A I –bit
B T-bit
C V-bit
D C-bit
Hide !
Answer B
QUESTION
Half carry is useful in ___________arithmetic.
A Addition
B Binary
C Hex
D BCD
Hide !
Answer D
QUESTION
Sign flag is exclusive OR of _________.
A I & T
B T & HC N & Z
D N & V
Hide !
Answer D
QUESTION
Negative flag when set indicates __________results.
A Negative
B Positive
C Neither
D Can not say
Hide !
Answer A
QUESTION
The stack is usually used for _________.
A Data
B Storing temporary data
C Return addresses
D All of these
Hide !
Answer D
QUESTIONStack is stored in ________.
A SRAM
B ROM
C DRAM
D EEPROM
Hide !
Answer A
QUESTION
Stack pointer register always points to ______ of stack.
A Bottom
B - 1
C Top
D Value
Hide !
Answer C
QUESTION
PUSH instruction _ the stack pointer by 1.
A Increments
B Decrements
C None of these
D Can not say
Hide !Answer B
QUESTION
_________instruction is used to remove data from stack.
A PUSH
B POP
C CALL
D RET
Hide !
Answer B
QUESTION
Stack pointer gets incremented by ________with the RET instructions.
A 1
B 2
C 3
D 4
Hide !
Answer B
QUESTION
Atmega 328 P has __________I/O registers.
A 16
B 32
C 64D 128
Hide !
Answer C
QUESTION
In Atmega 328P microcontroller , direction of a particular pin can be changed without changing others.
A True
B False
C Can not Say
D None
Hide !
Answer A
QUESTION
In Atmega 328 P Microcontroller, each output buffer has _______drive characteristics for high sink and source capability.
A Distinct
B Different
C Asymmetrical
D Symmetrical
Hide !
Answer D
QUESTION
The ________flag indicates a carry in arithmetic or logic operation.A Half Carry Flag
B Sign Flag
C Carry Flag
D None
Hide !
Answer C
QUESTION
The ________ indicates a zero result in an arithmetic or logic operation.
A Negative flag
B Zero Flag
C Sign Flag
D All of the above
Hide !
Answer B
QUESTION
Two’s Complement Overflow Flag supports ________arithmetic.
A 1’S Complement
B Two’s complement
C Three complement
D None
Hide !
Answer BQUESTION
A bit from a register in the Register File can be copied into T by the _________instruction.
A SEI
B CLI
C BST
D None
Hide !
Answer C
QUESTION
A bit in T can be copied into a bit in a register in the Register File by the ___________ instruction.
A BLD
B BST
C CLI
D SEI
Hide !
Answer A
QUESTION
The _________bit must be set for the interrupts to be enabled.
A Negative flag
B CLI
C T – bit
D Global Interrupt EnableHide !
Answer D
QUESTION
PC Stands for ___________.
A Personal computer
B Program counter
C Both
D None
Hide !
Answer B
QUESTION
The ATmega328/P Program Counter (PC) is 14 bits wide, thus addressing the _________ program memory locations.
A 32K
B 24K
C 16 K
D None
Hide !
Answer C
QUESTION
Atmega 328 P controller has ________Ports.
A 2B 3
C 4
D 5
Hide !
Answer B
QUESTION
The operating frequency of ATmega328 P Controller is ________.
A 12 MHz
B 16 MHz
C 18 MHz
D None
Hide !
Answer B
QUESTION
Port B of Atmega 328P Controller is ________bit wide.
A 8
B 5
C 7
D 3
Hide !
Answer AQUESTION
Port C of Atmega 328P Controller is ________bit wide.
A 5
B 6
C 7
D 8
Hide !
Answer C
QUESTION
Port D of Atmega 328P Controller is ________bit wide.
A 5
B 6
C 7
D 8
Hide !
Answer D
QUESTION
In Atmega 328P Controller Pin 9 and Pin 10 used as a____________.
A Port Pins
B Crystal Pins
C Power Supply Pins
D NoneHide !
Answer B
QUESTION
Atmega 328 P Controller has _______Timers.
A 2
B 4
C 3
D 5
Hide !
Answer C
QUESTION
Timer 0 is of _________bit wide.
A 64
B 32
C 16
D 8
Hide !
Answer D
QUESTION
Timer 1 is of ________bit wide.
A 16
B 32C 8
D 64
Hide !
Answer A
QUESTION
___________is the supply voltage pin for the A/D Converter.
A AVCC
B VCC
C GND
D None
Hide !
Answer A
QUESTION
Atmega 328 P Controller has _________channels for PWM.
A 2
B 3
C 5
D 6
Hide !
Answer D
QUESTIONAtmega 328 P controller consist of _____ digital pins and _________ analog pins.
A 14 , 6
B 13,9
C 12,8
D None
Hide !
Answer A
QUESTION
Arduino sketch consist of _________ and __________ functions.
A main and void
B If and else
C Void setup and void loop
D None
Hide !
Answer C
QUESTION
when a sketch starts after power-up or reset _______ function is run once.
A VOID
B MAIN
C Void setup
D None
Hide !Answer C
QUESTION
After setup() function, _______ function runs repeatedly.
A void loop
B Main
C void setup
D All the above
Hide !
Answer A
QUESTION
___________ function used to controls the arduino board until it is powered off or is reset.
A void setup
B void loop
C Main
D None
Hide !
Answer B
QUESTION
__________ Function used to initialize variables and pin modes, and to initialize any other libraries.
A void setup
B Main
C VoidD void loop
Hide !
Answer A
QUESTION
A _________ is an entity that does not change, where as a _________ is an entity that may change.
A Constants, Variable
B Keywords, Constant
C Variable, Keywords
D None
Hide !
Answer A
QUESTION
In Arduino IDE Sketch is stored with ______ extension.
A .ino
B .c
C .cc
D .asm
Hide !
Answer A
QUESTION
Data transmission rate is called as __________.A Data rate
B Baud Rate
C Bytes per sec
D None
Hide !
Answer B
QUESTION
When writing sketch Program Statements must end with a _________.
A semi-colon
B Full stop
C Question mark
D None
Hide !
Answer A
QUESTION
In Arduino IDE programm is also called as _________.
A Sketch
B Code
C Both
D None
Hide !
Answer AQUESTION
In Atmega 328P microcontroller, writing --------- to PINxn toggles the value of PORTxn
A 1
B 0
C either
D none
Hide !
Answer A
QUESTION
In Atmega 328P microcontroller, master clock input is the alternate function of --------
A PB7
B PB6
C PB5
D PB4
Hide !
Answer C
QUESTION
In Atmega 328P microcontroller, internal clock oscillators are connected to ------ and -------- respectively
A PB7 and PB6
B PB1 and PB2
C PB2 and PB3
D PB4 and PB5Hide !
Answer A
QUESTION
In Atmega 328P microcontroller, ----------- pin is Reset.
A PC6
B PB5
C PD5
D none
Hide !
Answer A
QUESTION
In Atmega 328P microcontroller, Pin number ----------- is Reset.
A 2
B 4
C 5
D 1
Hide !
Answer D
QUESTION
In Atmega 328P microcontroller, ----------- is USART external clock.
A PD3B PD4
C PD5
D none
Hide !
Answer B
QUESTION
Transducer is a device ----------------------
A Which converts one form of energy to another
B Which transmit current from one circuit to another
C Which transfer power
D none
Hide !
Answer A
QUESTION
Sensors are classified as ----------------
A Active and passive
B Primary and Secondary
C Analog and Digital
D All of the above
Hide !
Answer DQUESTION
What are the features of a sensor?
A Maintainability
B Ruggedness
C Speed
D All
Hide !
Answer D
QUESTION
Sensors are selected based on ----------------
A Variable to be measured
B Range of variables
C reliability
D All
Hide !
Answer D
QUESTION
Light sensors are also called as
A Optic sensors
B Photo sensors
C sensors
D noneHide !
Answer B
QUESTION
Which of the following is light sensor?
A Photo diode
B Photo transistor
C Light dependent resistor
D All
Hide !
Answer D
QUESTION
Which of the following is not a sensor?
A Photo diode
B Photo transistor
C Light dependent resistor
D Light emitting diode
Hide !
Answer D
QUESTION
In proximity sensors, the object may or may not be in contact with sensor.
A TRUE
B FALSEC Can't say
D None
Hide !
Answer A
QUESTION
Example of non-contact sensors is -------
A capacitive
B inductive
C optical
D all
Hide !
Answer D
QUESTION
Example of contact sensors is
A capacitive
B inductive
C optical
D none
Hide !
Answer D
QUESTIONFor capacitive sensors, C is given by
A C = ε A / d
B C = A d / ε
C C = ε d / A
D none
Hide !
Answer A
QUESTION
Proximity sensors might use reluctance or capacitance principles.
A TRUE
B FALSE
C Can't say
D None
Hide !
Answer A
QUESTION
------------------ type sensor is used for angular position sensing.
A Opto- electronic
B Optical
C Ultrasonic
D Hall effect
Hide !Answer D
QUESTION
Optical encoders convert ---------------- into digital signals
A Linear motion
B Rotary motion
C both
D none
Hide !
Answer C
QUESTION
Proximity sensors convert---------- into electrical signals.
A Linear
B Rotary
C both
D None
Hide !
Answer D
QUESTION
transforms output of a controller to motion.
A Optical encoders
B Actuators
C AccumulatorsD Sensors
Hide !
Answer B
QUESTION
Actuator transforms output of a controller to motion.
A TRUE
B FALSE
C Can't say
D none
Hide !
Answer A
QUESTION
Accumulators transforms output of a controller to motion.
A TRUE
B FALSE
C Can't say
D none
Hide !
Answer B
QUESTION
Which of the following is actuator?A DC motor
B Solenoid valve
C Relay
D All
Hide !
Answer D
QUESTION
Which of the following is not an actuator?
A DC motor
B Solenoid valve
C Relay
D LVDT
Hide !
Answer D
QUESTION
Which of the following is temperature sensor?
A LM35
B Thermometer
C Thermister
D All
Hide !
Answer DQUESTION
Which of the following is temperature sensor?
A LM35
B MQ5
C MQ6
D LM25
Hide !
Answer A
QUESTION
Which of the following transducer is used for pressure mesurement?
A LVDT
B RTD
C Strain Guage
D Accelerometers
Hide !
Answer C
QUESTION
Which of the following converts linear motion into electrical signals?
A LVDT
B RTD
C Strain Guage
D AccelerometersHide !
Answer A
QUESTION
Linear Variable Differential Transformer is ------------------ type of transducer
A capacitive
B inductive
C optical
D none
Hide !
Answer B
QUESTION
Which of the following measures acceleration?
A LVDT
B RTD
C Strain Guage
D Accelerometers
Hide !
Answer D
QUESTION
Which of the following measures deformation in a quartz crystal
A Piezoelectric transducerB LVDT
C RTD
D Capacitive sensor
Hide !
Answer C
QUESTION
DAS is responsible for -----------
A Acquiring data
B Converting it into usable data
C Putting it in suitable form
D all
Hide !
Answer D
QUESTION
_________ is used to bring data in suitable form.
A ADC
B DAC
C Both
D None
Hide !
Answer CQUESTION
Which of the following is not the part of DAS?
A MUX
B ADC
C Micro-controller
D None
Hide !
Answer D
QUESTION
Which of the following is the part of DAS?
A MUX
B ADC
C Micro-controller
D All
Hide !
Answer D
QUESTION
........ is necessary when the distance between transducers and display device is large.
A Attenuator
B Prescalar
C Multiplexer
D NoneHide !
Answer D
QUESTION
.............. is used to select one of the transducers connected to DAS.
A Attenuator
B Prescalar
C Multiplexer
D None
Hide !
Answer C
QUESTION
Strip – chart recorders, X-Y recorders, magnectic recorders are used to record data.
A TRUE
B FALSE
C Can't say.
D None
Hide !
Answer A
QUESTION
Input voltage range for Arduino is------------ V.
A 5 – 10
B 0 - 5C 7 – 10
D 7 – 12
Hide !
Answer D
QUESTION
Arduino Uno has ---------number of analog inputs.
A 3
B 5
C 6
D 7
Hide !
Answer C
QUESTION
Atmega 328P has ------channel ADC
A 3
B 5
C 6
D 7
Hide !
Answer C
QUESTIONWhat is the resolution of ADC in Atmega 328P micro-controller?
A 8 bit
B 10 bit
C 6 bit
D 4 bit
Hide !
Answer B
QUESTION
Arduino Uno has -----------number of digital I/O pins
A 10
B 14
C 12
D 16
Hide !
Answer B
QUESTION
Arduino Uno has------ KB flash memory.
A 8
B 16
C 32
D 64
Hide !Answer C
QUESTION
Arduino Uno has ----------------KB RAM
A 1
B 2
C 4
D 8
Hide !
Answer B
QUESTION
Atmega 328 P controller has ________Ports.
A 2
B 3
C 4
D 5
Hide !
Answer B
QUESTION
The operating frequency of Arduino Uno is ________.
A 12 MHz
B 16 MHz
C 18 MHzD None
Hide !
Answer B
QUESTION
Port B of Atmega 328P Controller is ________bit wide.
A 8
B 5
C 7
D 3
Hide !
Answer A
QUESTION
Port C of Atmega 328P Controller is ________bit wide.
A 5
B 6
C 7
D 8
Hide !
Answer C
QUESTION
Digital pin 0 and pin 1 is used forA Rx and Tx
B Xtal 1 and Xtal 2
C Vcc and GND
D Avref and AVcc
Hide !
Answer A
QUESTION
In Atmega 328P Controller Pin 9 and Pin 10 used as a____________.
A Port Pins
B Crystal Pins
C Power Supply Pins
D None
Hide !
Answer B
QUESTION
Message area in IDE is capable of showing errors. Say true or false
A TRUE
B FALSE
C Can't say
D none
Hide !
Answer AQUESTION
_________ provide extra functionality like manipulating data
A Boot loader
B IDE
C Sketchbook
D Libraries
Hide !
Answer D
QUESTION
Board selection Arduino IDE is done for setting
A CPU speed
B Baud rate
C both
D None of these
Hide !
Answer C
QUESTION
Baudrate can be set in ---- of Arduino IDE.
A Board selection
B Serial monitor
C Library
D SketchbookHide !
Answer B
QUESTION
Arduino Pro Mini is equivalent to ------------
A Arduino Mega
B Arduino Fio
C Arduino Esplora
D Arduino Gemma
Hide !
Answer B
QUESTION
Arduino Uno consists of _____ digital pins and _________ analog pins.
A 14 , 6
B 13,9
C 12,8
D None
Hide !
Answer A
QUESTION
Arduino sketch consist of _________ and __________ functions.
A main and voidB If and else
C setup and loop
D None
Hide !
Answer C
QUESTION
when a sketch starts after power-up or reset _______ function is run once.
A VOID
B MAIN
C Void setup
D None
Hide !
Answer C
QUESTION
After setup() function, _______ function is runs repeatedly.
A void loop
B Main
C void setup
D All the above
Hide !
Answer AQUESTION
___________ function used to controls the arduino board until it is powered off or is reset.
A void setup
B void loop
C Main
D None
Hide !
Answer B
QUESTION
__________ Function used to initialize variables and pin modes, and to initialize any other libraries.
A void setup
B Main
C Void
D void loop
Hide !
Answer A
QUESTION
Char takes------------amount of memory.
A 1 byte
B 4 bytes
C 2 bytes
D 1 bitHide !
Answer A
QUESTION
A byte stores 8- bit unsigned numbers from -------to ------------
A 1 to 256
B 0 to 255
C both
D none
Hide !
Answer B
QUESTION
Arduino Uno, int stores ---------------value.
A 4 bit
B
8 bit
C 16 bit
D 32 bit
Hide !
Answer C
QUESTION
Int stores negative numbers by a technique called 1's complement. Say true or false.
A TRUE
B FALSEC Can't say
D none
Hide !
Answer B
QUESTION
Long variables store _________ bits.
A 8 bit
B 16 bit
C 32 bit
D 64 bit
Hide !
Answer C
QUESTION
Double occupies _________ bytes.
A 1
B 2
C 4
D 8
Hide !
Answer C
QUESTIONA group of instructions that perform a specific task is called as
A function
B subroutine
C procedure
D all
Hide !
Answer D
QUESTION
Which of the following is/are the advantage(s) of using functions?
A Make debugging a code simple
B Make the whole sketch smaller and more compact
C Make it easier to reuse code
D All of the above
Hide !
Answer D
QUESTION
--------- Function generates a square wave of specified frequency on a pin.
A tone()
B square()
C duty()
D None of the above
Hide !Answer A
Unit-4 Introduction to Microcontrollers MCQ's Part-B
Edit
QUESTION
In AVR, which of the following registers are not used for programming timers?
A) TCNT
B) TCON
C) TIFR
D) none of the mentioned
Hide !
Answer: B
Explanation: In the timer programming of an AVR micro controller,mainly used registers are TCNTn that stores the values of the count. TCCRn
that is used to assign the mode of operation of a timer and TIFR that stores the status of various flags of the timers. Two more registers are
used they are OCRn and OCFn. They are used for comparison with the count register.
QUESTION
What is the use of the prescalar in the operation of the timer?
A) for fast calculations
B) for increasing the time delay given by the timer by decreasing its frequency of operation
C) for removing the concept the reloading of count
D) for easy counter operations
Hide !Answer: B
Explanation: Prescalars are used in the operation of the timers because they generally increase the time delay generation by deceasing the
frequency of its operation.
QUESTION
What modes are generally used in the operation of the timer0?
A) normal mode
B) CTC mode
C) PWM mode
D) all of the mentioned
Hide !
Answer: D
Explanation: Modes of a timer are decided by the WGM00 and WGM01 bit of the TCCR0 register and for timer0 these modes are normal mode,
CTC mode, pwm mode and the fast pwm mode.
QUESTION
Timer 0 can act as a counter
A) if the CS02-CS00 are 110 or 111
B) if the FOC0 bit is set to 110
C) none of the mentioned
D) all of the mentioned
Hide !
Answer: A
Explanation: Timer0 can act as a counter if the CS02-CS00 bits are from 110-111.QUESTION
Which of the timer can operate in the 16 bit condition?
A) timer0
B) timer1
C) timer2
D) all of the mentioned
Hide !
Answer: B
Explanation: Timer0 and Timer2 can operate in the 8 bit condition while only Timer 1 operates in the 16 bit condition.
QUESTION
Which of the following will generate the maximum time delay?
A) f/2
B) f/4
C) f/16
D) f/32
Hide !
Answer: D
Explanation: f/32 has the lowest frequency as it is divided by the maximum value of the constant, so as time and frequency are inversely related
to each other so this will generate the maximum amount of machine cycle which will as a result generate the greatest delay.
QUESTION
What is the difference in operation of a normal and a CTC mode of a timer?
A) in CTC mode PWM is usedB) here serial timer is monitored
C) her the contents are compared with the OCR register, if value becomes equal then only the timer is cleared
D) none of the mentioned
Hide !
Answer: C
Explanation: In CTC mode of a timer the contents of the counter register are compared with the OCR register to clear the flag for the roll over
condition to come.
QUESTION
We can count the pulses on the positive or the negative edge triggered pulse of the clock?
A) true
B) false
C) can’t be determined
D) depends on the circumstances
Hide !
Answer: A
Explanation: A counter can count pulses on the positive or the negative edge of the clock. 9. Which pin is used for the input clock of the
counter0?
QUESTION
We can count the pulses on the positive or the negative edge triggered pulse of the clock?
A) true
B) false
C) can’t be determined
D) depends on the circumstancesHide !
Answer: A
Explanation: A counter can count pulses on the positive or the negative edge of the clock.
QUESTION
Which pin is used for the input clock of the counter0?
A) PORTB.0
B) PORTB.1
C) PORTB.2
D) PORTB.3
Hide !
Answer: A
Explanation: PORTB.0 is used for the input clock of the counter0 in AVR micro controllers.
QUESTION
Which resource provides clock pulse to AVR timers if CS02-00=6?
A) internal clock of the AVR
B) external clock of the AVR
C) none of the mentioned
D) all of the mentioned
Hide !
Answer: B
Explanation: External clock is used for providing the pulse to the AVR timers if CS02-00=6.
QUESTIONIs the following instruction correct LDI R3,50?
A) Yes
B) No
C) Cant be said
D) none of the mentioned
Hide !
Answer: B
Explanation: If LDI Rd,k is written then the range of Rd varies from R16-R31, as R3 is less than R16 so this instruction will generate an error.
QUESTION
Registers R0-R31 are used for what type of works?
A) they are used for arithmetic and logic instructions
B) they are used for data copy
C) they are used for calculations
D) none of the mentioned
Hide !
Answer: A
Explanation: GPRs are used for implementing arithmetic and logic instructions in the
controller. They do the same work as the accumulator does in the other micro controllers and micro processors.
QUESTION
Largest value that can be loaded in an 8 bit register is?
A) 11111111H
B) FH
C) FFHD) 00H
Hide !
Answer: C
Explanation: The largest value that can be loaded in an 8 bit register is 11111111b or FFH.
QUESTION
The total space for the data memory available in the AVR based micro controller is?
A) FFH
B) FFFH
C) FFFFH
D) FFFFFH
Hide !
Answer: C
Explanation: The maximum value that can be loaded in the code memory of an AVR based micro controller is FFFFH.
QUESTION
Which out of the following instructions don’t affect the flags of the status register?
A) AND
B) INC
C) OR
D) ADD
Hide !
Answer: D
Explanation: ADD command does not affect the flags of the status register. It just adds the contents of the two registers together.QUESTION
What is the difference between the two given instructions? LDI R16,0x34 and LDI R16,$34
A) One copies the hexadecimal value to R16 and the other copies the decimal value to the R16 register
B) One is for command, other is for data
C) One is for assignment, other is for operations
D) Both the commands are the same
Hide !
Answer: D
Explanation: Both the above commands are the same. They both are used for assigning the hexadecimal values to the registers.
QUESTION
Which out of the following is not a directive?
A) .EQU
B) .DEVICE
C) .ORG
D) .LDI
Hide !
Answer: D
Explanation: .EQU, .DEVICE, .ORG all are the directives to the assembler whereas LDI is a command.
QUESTION
Is an assembly language a high level language?
A) Yes
B) NoC) Cant be said
D) none of the mentioned
Hide !
Answer: B
Explanation: High Level Languages are the languages that are written in the common english, so that even a common man can understand it
easily like C,C++, whereas assembly language is a middle level language between the high level and the machine level.
QUESTION
A 14 bit program counter can execute a maximum of _________ memory locations?
A) 4K
B) 8K
C) 16K
D) 64K
Hide !
Answer: C
Explanation: A program counter of an AVR is 14 bit long which means it has 2^14 bytes of memory or 16K bytes of memory.
QUESTION
When AVR wakes up, then the value of PC becomes?
A) 00H
B) 000H
C) 0000H
D) 00000H
Hide !Answer: D
Explanation: When an AVR wakes up, then the PC starts at the memory location 00000H
QUESTION
On power on SP points to the address?
A) ffffH
B) fffH
C) 00h
D) all of the mentioned
Hide !
Answer: C
Explanation: On power on SP register points to the 00H address.
QUESTION
How many times setup() runs?
A) 1 Time
B) 2 Times
C) infinite times
D) 0 times
Hide !
Answer- A
QUESTION
How many times loop() runs?
A) 1 TimeB) 2 Times
C) infinite times
D) 0 times
Hide !
Answer- C
QUESTION
PWM stands for
A) Pulse With Modulation
B) Pin Width Modulation
C) Pulse Width Modulation
D) Pulse Width Mode
Hide !
Answer- B
QUESTION
PWM output varies from
A) 0 to 255
B) 0 to 5
C) 0 to 1023
D) 0 to 256
Hide !
Answer- AQUESTION
Which language is the Arduino IDE written in?
A) Java
B) C
C) C++
D) PHP
Hide !
Answer- A
QUESTION
In delay(t); t is in :
A) microsec
B) millisec
C) nanosec
D) sec
Hide !
Answer- B
QUESTION
If Serial is begun with Serial.begin(9600); How much time will it take to send 2 ASCII characters?
A) 1.667 millisecond
B) 1.9220 millisecond
C) 4.800 millisecond
D) 1.9200 millisecondHide !
Answer- A
QUESTION
How many analog ports does an Arduino have?
A) five, and they are labeled A1-A5
B) six, and they are labeled A0-A5
C) six, and they are labeled A1-A6
D) five, and they are labeled A0-A4
Hide !
Answer- B
QUESTION
An Arduino’s microcontroller is pre-programmed with a _______ that simplifies uploading of programs to the on-chip flash memory, compared
with other devices that typically need an external chip programmer
A) personal computer
B) bootloader
C) computer
D) operating system
Hide !
Answer- B
QUESTION
Which of the timer can operate in the 16 bit condition?
A) timer0B) timer1
C) timer2
D) all of the mentioned
Hide !
Answer: B
Explanation: Timer0 and Timer2 can operate in the 8 bit condition while only Timer 1 operates in the 16 bit condition.
QUESTION
Which of the following will generate the maximum time delay?
A) f/2
B) f/4
C) f/16
D) f/32
Hide !
Answer: d
Explanation: f/32 has the lowest frequency as it is divided by the maximum value of the constant, so as time and frequency are inversely related
to each other so this will generate the maximum amount of machine cycle which will as a result generate the greatest delay.
QUESTION
What is the difference in operation of a normal and a CTC mode of a timer?
A) in CTC mode PWM is used
B) here serial timer is monitored
C) her the contents are compared with the OCR register, if value becomes equal then only the timer is cleared
D) none of the mentionedHide !
Answer: C
Explanation: In CTC mode of a timer the contents of the counter register are compared with the OCR register to clear the flag for the roll over
condition to come.
QUESTION
We can count the pulses on the positive or the negative edge triggered pulse of the clock?
A) true
B) false
C) can’t be determined
D) depends on the circumstances
Hide !
Answer: A
Explanation: A counter can count pulses on the positive or the negative edge of the clock.
QUESTION
8. We can count the pulses on the positive or the negative edge triggered pulse of the clock?
A) true
B) false
C) can’t be determined
D) depends on the circumstances
Hide !
Answer: A
Explanation: A counter can count pulses on the positive or the negative edge of the clock.QUESTION
Which pin is used for the input clock of the counter0?
A) PORTB.0
B) PORTB.1
C) PORTB.2
D) PORTB.3
Hide !
Answer: A
Explanation: PORTB.0 is used for the input clock of the counter0 in AVR micro controllers.
QUESTION
Which resource provides clock pulse to AVR timers if CS02-00=6?
A) internal clock of the AVR
B) external clock of the AVR
C) none of the mentioned
D) all of the mentioned
Hide !
Answer: B
Explanation: External clock is used for providing the pulse to the AVR timers if CS02-00=6.
QUESTION
Is the following instruction correct LDI R3,50?
A) Yes
B) No
C) Cant be saidD) none of the mentioned
Hide !
Answer: B
Explanation: If LDI Rd,k is written then the range of Rd varies from R16-R31, as R3 is less than R16 so this instruction will generate an error.
QUESTION
Registers R0-R31 are used for what type of works?
A) they are used for arithmetic and logic instructions
B) they are used for data copy
C) they are used for calculations
D) none of the mentioned
Hide !
Answer: a
Explanation: GPRs are used for implementing arithmetic and logic instructions in the
controller. They do the same work as the accumulator does in the other micro controllers and micro processors.
QUESTION
Largest value that can be loaded in an 8 bit register is?
A) 11111111H
B) FH
C) FFH
D) 00H
Hide !
Answer: CExplanation: The largest value that can be loaded in an 8 bit register is 11111111b or FFH.
QUESTION
The total space for the data memory available in the AVR based micro controller is?
A) FFH
B) FFFH
C) FFFFH
D) FFFFFH
Hide !
Answer: C
Explanation: The maximum value that can be loaded in the code memory of an AVR based micro controller is FFFFH.
QUESTION
Which out of the following instructions don’t affect the flags of the status register?
A) AND
B) INC
C) OR
D) ADD
Hide !
Answer: D
Explanation: ADD command does not affect the flags of the status register. It just adds the contents of the two registers together.
QUESTION
What is the difference between the two given instructions? LDI R16,0x34 and LDI R16,$34
A) One copies the hexadecimal value to R16 and the other copies the decimal value to the R16 registerB) One is for command, other is for data
C) One is for assignment, other is for operations
D) Both the commands are the same
Hide !
Answer: D
Explanation: Both the above commands are the same. They both are used for assigning the hexadecimal values to the registers.
QUESTION
Which out of the following is not a directive?
A) .EQU
B) .DEVICE
C) .ORG
D) .LDI
Hide !
Answer: D
Explanation: .EQU, .DEVICE, .ORG all are the directives to the assembler whereas LDI is a command.
QUESTION
Is an assembly language a high level language?
A) Yes
B) No
C) Cant be said
D) none of the mentioned
Hide !Answer: B
Explanation: High Level Languages are the languages that are written in the common english, so that even a common man can understand it
easily like C,C++, whereas assembly language is a middle level language between the high level and the machine level.
A 14 bit program counter can execute a maximum of _________ memory locations?
A) 4K
B) 8K
C) 16K
D) 64K
Hide !
Answer: C
Explanation: A program counter of an AVR is 14 bit long which means it has 2^14 bytes of memory or 16K bytes of memory.
QUESTION
When AVR wakes up, then the value of PC becomes?
A) 00H
B) 000H
C) 0000H
D) 00000H
Hide !
Answer: D
Explanation: When an AVR wakes up, then the PC starts at the memory location 00000H
QUESTION
On power on SP points to the address?A) ffffH
B) fffH
C) 00h
D) all of the mentioned
Hide !
Answer: C
Explanation: On power on SP register points to the 00H address.
QUESTION
How many times setup() runs?
A) 1 Time
B) 2 Times
C) infinite times
D) 0 times
Hide !
Answer- A
23. How many times loop() runs?
A) 1 Time
B) 2 Times
C) infinite times
D) 0 times
Hide !
Answer- CQUESTION
PWM stands for
A) Pulse With Modulation
B) Pin Width Modulation
C) Pulse Width Modulation
D) Pulse Width Mode
Hide !
Answer- B
QUESTION
PWM output varies from
A) 0 to 255
B) 0 to 5
C) 0 to 1023
D) 0 to 256
Hide !
Answer- A
QUESTION
Which language is the Arduino IDE written in?
A) Java
B) C
C) C++
D) PHPHide !
Answer- A
QUESTION
In delay(t); t is in :
A) microsec
B) millisec
C) nanosec
D) sec
Hide !
Answer- B
QUESTION
If Serial is begun with Serial.begin(9600); How much time will it take to send 2 ASCII characters?
A) 1.667 millisecond
B) 1.9220 millisecond
C) 4.800 millisecond
D) 1.9200 millisecond
Hide !
Answer- A
How many analog ports does an Arduino have?
A) five, and they are labeled A1-A5
B) six, and they are labeled A0-A5C) six, and they are labeled A1-A6
D) five, and they are labeled A0-A4
Hide !
Answer- B
QUESTION
An Arduino’s microcontroller is pre-programmed with a _______ that simplifies uploading of programs to the on-chip flash memory, compared
with other devices that typically need an external chip programmer
A) personal computer
B) bootloader
C) computer
D) operating system
Hide !
Answer- B