ORDERING OF SENTENCES QUIZ

What will happen if the back emf of a dc motor vanishes suddenly?

The motor will run noisy

The armature may burn

The motor will continue to run

The motor will stop

TRUE ANSWER : ?
YOUR ANSWER : ?

Excessive motor vibration is caused by

Bent shaft

Worn bearings

Open armature coil

Too much brush tension

TRUE ANSWER : ?
YOUR ANSWER : ?

Dc series motors are used in those applications where _____ is required.

High starting torque

Constant speed

Low no load speed

None of the listed here

TRUE ANSWER : ?
YOUR ANSWER : ?

The speed of a series motor at no load is

1000 rpm

Infinity

4000 rpm

2000 rpm

TRUE ANSWER : ?
YOUR ANSWER : ?

Which of the following can be used for controlling the speed of a dc motor?

Thermistor

Thyristor

Transistor

Thyratron

TRUE ANSWER : ?
YOUR ANSWER : ?

The mechanical power developed by a shunt motor will be maximum when the ratio of back emf to applied voltage is

0.5

4.0

1.0

2.0

TRUE ANSWER : ?
YOUR ANSWER : ?

The back emf in a dc motor ______

Aids the applied voltage

Aids the armature current

Opposes the applied voltage

None of the listed here

TRUE ANSWER : ?
YOUR ANSWER : ?

The armature torque of the D.C. shunt motor is proportional to

both (A) and (B)

field flux only

None of these

armature current only

TRUE ANSWER : ?
YOUR ANSWER : ?

If conditions for maximum power for a dc motor are established, the efficiency of the motor will be

Less than 50%

100 %

60 to 70 %

80 to 90 %

TRUE ANSWER : ?
YOUR ANSWER : ?

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

Anywhere between 75% and 90%

Less than 50%

Around 90%

1

TRUE ANSWER : ?
YOUR ANSWER : ?

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