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

The starting resistance of a D.C. motor is generally_______________?

A. Low
B. Around 500 q
C. 1000 q
D. Infinitely large

Which of the following load normally needs starting torque more than the rated torque?

A. Blowers
B. Conveyors
C. Air compressors
D. Centrifugal pumps

Which of the following law/rule can he used to determine the direction of rotation of D.C. motor ?

A. Lenz’s law
B. Faraday’s law
C. Coloumb’s law
D. Fleming’s left-hand rule

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

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

In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be______________?

A. 100%
B. Around 90%
C. Anywhere between 75% and 90%
D. Less than 50%

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

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

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