Top 150+ Solved DC Motor MCQ Questions Answer
Q. In case of D.C. shunt motors the speed is dependent on back e.m.f. only because
a. back e.m.f. is equal to armature drop
b. armature drop is negligible
c. flux is proportional to armature current
d. flux is practically constant in D:C. shuntmotors
Q. In a D.C. shunt motor, under the conditions of maximum power, the current inthearmature will be
a. almost negligible
b. rated full-load current
c. less than full-load current
d. more than full-load current
Q. By looking at which part of the motor, it can be easily confirmedthat a particularmotor is D.C. motor?
a. Frame
b. Shaft
c. Commutator
d. Stator
Q. In which of the following applications D.C. series motor is invariably tried?
a. Starter for a car
b. Drive for a water pump
c. Fan motor
d. Motor operation in A.C. or D.C.
Q. In which of the following applications D.C. series motor is invariably tried?
a. Starter for a car
b. Drive for a water pump
c. Fan motor
d. Motor operation in A.C. or D.C.
Q. In D.C. machines fractional pitch winding is used
a. to improve cooling
b. to reduce copper losses
c. to increase the generated e.m.f.
d. to reduce the sparking
Q. A three point starter is considered suitable for
a. shunt motors
b. shunt as well as compound motors
c. shunt, compound and series motors
d. all D.C. motors
Q. In case-the conditions for maximum power for a D.C. motor are established, theefficiency of the motor will be
a. 100%
b. around 90%
c. anywhere between 75% and 90%
d. less than 50%
Q. The ratio of starting torque to full-load torque is least in case of
a. series motors
b. shunt motors
c. compound motors
d. none of the above
Q. In D.C. motor which of the following can sustain the maximum temperature rise?
a. Slip rings
b. Commutator
c. Field winding
d. Armature winding
Q. Which of the following law/rule can he used to determine the direction of rotation ofD.C. motor ?
a. Lenz's law
b. Faraday's law
c. Coloumb's law
d. Fleming's left-hand rule
Q. Which of the following load normally needs starting torque more than the ratedtorque?
a. Blowers
b. Conveyors
c. Air compressors
d. Centrifugal pumps
Q. The starting resistance of a D.C. motor is generally
a. low
b. around 500 Q
c. 1000 Q
d. infinitely large
Q. The speed of a D.C. series motor is
a. proportional to the armature current
b. proportional to the square of the armature current
c. proportional to field current
d. inversely proportional to the armature current
Q. In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to
a. 100% of the previous value
b. 50% of the previous value
c. 25% of the previous value
d. 10% of the previous value