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MCQ of D.C motor page-2


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11. Shunt motor has

a) Low speed at high loads and high speed at low loads
b) Low speed at low loads and high speed at low loads
c) Widely varying speed
d) Constant speed

Ans: (d)

12. If a d.c. motor is connected across a.c. supply, the motor will

a) Run at lower speed
b) Burn
c) Run at normal speed
d) Run continuously but for sparking at brushes

Ans: (b)

13. If field current of a shunt motor is changed, then

a) Torque remains constant but h.p. will change
b) Horse power remains constant but torque will change
c) Both remains constant
d) Both will change

Ans: (b)

14. In series-parallel control method when two d.c. series motors are connected in series, speed of the set is

a) Half of the speed of the motors
b) Rated speed of any of the motors
c) One-fourth of the speed of the motors
d) Same as in parallel

Ans: (c)

15. The torque produced by a series combination of two d.c. series motor is

a) Half the torque when they are connected in parallel
b) Twice the torque when they are connected in parallel
c) Four times the torque when they are connected in parallel
d) Equal to the torque when they are connected in parallel

Ans: (c)

16. Synchronous reactance is defined as reactance

a) Due to armature reaction and leakage of flux both
b) Due to armature reaction of the machine
c) Due to leakage flux
d) Of synchronous machine

Ans: (a)

17. Armature winding of a series motor is excited

a) Resistively
b) Conductively
c) Inductively
d) None of these

Ans: (b)

18. Speed of a d.c. motor depends upon

a) Field flux
b) Armature resistance
c) Applied voltage
d) All of these

Ans: (d)

19. For most of the application purpose

a) Depends on requirement
b) Compound motor is used
c) Shunt motor is used
d) Series motor is used

Ans: (a)

20. Use of the starter in d.c. motors is necessary because

a) They are not self-starting
b) To light the high initial current by inserting high resistance
c) To overcome back emf
d) None of these

Ans: (b)


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