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MCQ of D.C motor page-1MCQ of D.C motor page-2MCQ of D.C motor page-3MCQ of D.C motor page-4Multiple Choice Question (MCQ) of D.C. Machines page-1Multiple Choice Question (MCQ) of D.C. Machines page-2Multiple Choice Question (MCQ) of D.C. Machines page-3Multiple Choice Question (MCQ) of D.C. Machines page-4Multiple Choice Question (MCQ) of D.C. Machines page-5Multiple Choice Question (MCQ) of D.C. Machines page-6Multiple Choice Question (MCQ) of D.C. Machines page-7Multiple Choice Question (MCQ) of D.C. Machines page-8Multiple Choice Question (MCQ) of D.C. Machines page-9Multiple Choice Question (MCQ) of D.C. Machines page-10MCQ of D.C motor page-5MCQ of D.C motor page-6MCQ of D.C motor page-7MCQ of D.C motor page-8MCQ of D.C motor page-9MCQ of D.C motor page-10MCQ of D.C motor page-11MCQ of D.C motor page-12MCQ of D.C motor page-13MCQ of D.C motor page-14MCQ of D.C motor page-15MCQ of D.C motor page-16MCQ of D.C motor page-17MCQ of D.C motor page-18

Index

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-Power

MCQ of D.C motor page-6


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11. The mechanical power developed by a dc motor is maximum when the ratio of back emf/applied voltage is

A) 0.7
B) 0.5
C) 3.0
D) 1.0.

Ans : (B)

12. If the load current and flux of a dc motor are held constant and voltage applied across its armature is increased by 5 percent, the peed of motor will be

A) increases by about 5%
B) reduce by about 5%
C) remain unaltered
D) depend on other factors.

Ans : (A)

13. A dc motor develops a torque of 140 N-m at 1400 rpm. If the motor now runs at 1000 rpm, the torque developed will be

A) 51 N-m
B) 71 N-m
C) 1000 N-m
D) 196 N-m.

Ans : (D)

14. In a dc shunt motor if the supply voltage is increased by 10%, which of the following will increase ?

A) Full load speed
B) Full load current
C) Starting torque
D) All of the above.

Ans : (A)

15. The type of dc motor control preferred for applications where unusually wide and very sensitive speed control is required will be

A) Flux control
B) Voltage control
C) Ward-Leonard control
D) Armature control.

Ans : (C)

16. The relationship between back emf and applied voltage in case of a dc motor is given by

A) Eb = 2 V - IaRa
B) Eb = 2 V + IaRa
C) Eb = V - IaRa
D) Eb = V + IaRa

Ans : (C)

17. The magnetic of mechanical force in a dc motor is dependent on

A) cross section area of the conductor
B) length of the conductor
C) nature of material of the conductor
D) none of these.

Ans : (B)

18. The current drawn by a dc motor at the starting instant will be

A) V/Ra
B) Eb/Ra
C) V/2Ra
D) 2 V/Ra.

Ans : (A)

19. If the back emf in a dc motor vanishes suddenly, the motor will

A) run at very low speed
B) run at very high speed
C) burn
D) start hunting.

Ans : (C)

20. The maximum speed ratio obtainable in a Ward Leonard control, the dc motor is

A) 2 : 1
B) 5 : 1
C) 25 : 1
D) 250 : 1.

Ans : (C)


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