1. The generated e.m.f and the current are in the opposite direction in case of ?

d.c. generators

d.c. motors

both (a) and (b)

none of the above

Answer: d.c. motors

Explanation:


2. While starting a differential compound motor, it is best to short the series field in order to avoid ?

excessive starting period

motor starting in wrong direction

tripping of the circuit breaker

large in rush of current

Answer: motor starting in wrong direction

Explanation:


3. Which D.C. motor has got maximum self relieving property ?

Series motor

Shunt motor

Cumulatively compounded motor

Differentially compounded motor

Answer: Series motor

Explanation:


4. If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens ?

this will make armature to take heavy current, possibly burning it

this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses

nothing will happen to motor

motor will come to stop

Answer: this will make armature to take heavy current, possibly burning it

Explanation:


5. The armature voltage control of D.C. motor provides ?

constant torque drive

constant voltage drive

constant current drive

none of the above

Answer: none of the above

Explanation:


6. A motor for punching machine is usually subjected to ?

no load

continuous part load

continuous full load

intermittent Load

Answer: intermittent Load

Explanation:


7. When the armature of a D.C. motor rotates, e.m.f. induced is ?

self-induced e.m.f.

mutually induced e.m.f.

back e.m.f.

none of the above

Answer: back e.m.f.

Explanation:


8. If the speed of a D.C. shunt motor is increased the back e.m.f. of the motor will ?

decrease

increase

remain same

become zero

Answer: increase

Explanation:


9. Sparking is discouraged in a D.C. motor because ?

it increases the input power consumption

commutator gets damaged

both (a) and (b)

none of the above

Answer: commutator gets damaged

Explanation:


10. Which D.C. motor bas got maximum self loading property ?

Series motor

Shunt motor

Cumulatively compounded motor

Differentially compounded motor

Answer: Differentially compounded motor

Explanation: