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SymbolsTransformerRelayPower-SystemBasic-electricalACSR-ConductorCircuit-BreakerInterview-questions-of-Basic-ElectricityInterview-questions-of-transformerInsulatorCurrent-TransformerMCQMCQ-powersystemThermal-power-stationInterview-questions-of-Power-SystemPower-ElectronicsInterview-questions-of-Underground-CableInterview-questions-of-IlluminationIlluminationMCQ-of-ElectronicsMCQ-of-Basic-ElectricalMCQ-of-Transformers MCQ-of-D.C-motor MCQ-of-D.C-generatorsMCQ-Control-SystemMCQ-Measurementsmcq-of-Generation-power-systemMCQ-of-Induction-MotorMCQ-of-Transmission-DistributionMCQ-of-Electrical-MachinesMCQ-of-Alternator-and-Synchronous-MotorsMCQ-Electric-PowerMCQ-Illumination

MCQ of D.C motor page-7


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21. A dc motor can be easily identified by looking at

A) yoke
B) commutator
C) winding
D) frame.

Ans : (B)

22. If the flux of dc motor approaches zero

A) the motor will tend to run at infinite speed
B) the motor will stop
C) its speed will remain unchanged
D) its speed will approach zero.

Ans : (A)

23. In a rotating electric machine, the torque produced will be maximum when

A) torque angle is zero
B) torque angle is 90o
C) two magnetic fields are aligned with each other
D) field strength are maximum and torque angle is zero.

Ans : (B)

24. For the operation of milling machine, the following motor is used

A) DC short shunt compound motor
B) DC compound motor
C) DC shunt motor
D) DC series motor.

Ans : (C)

25. In Ward, Leonard control the lower limit of speed is imposed by

A) core losses of motor
B) residual magnetism of the generator
C) mechanical losses of motor and generator together
D) all of the above.

Ans : (B)

26. If the applied voltage of a dc shunt motor is halved with the load torque doubled, the armature current will be

A) halved
B) zero
C) unaltered
D) doubled.

Ans : (D)

27. Change in speed of motor, under Ward Leonard control, occurs due to change in

A) armature voltage of dc motor
B) armature current of dc motor
C) field excitation of dc motor
D) supply voltage.

Ans : (A)

28. The starting resistance of a dc motor is usually

A) low
B) around 100 ohms
C) very large
D) infinitely large.

Ans : (A)

29. A dc shunt motor is running at light load. What will happen if the field winding gets opened ?

A) motor will stop
B) motor will burn
C) motor will pick up high speed
D) motor will make noise.

Ans : (C)

30. The speed torque characteristic of a series motor is a/an

A) Hyperbola
B) Ellipse
C) Parabola
D) Circle.

Ans : (A)


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