Electrical Engineering Mcqs Practice Test

Question 1

Sparking, is discouraged in a D.C. motor because_____________?

Accepted Answer

B. commutator gets damaged

Question 2

Three point starter can be used for______________?

Accepted Answer

D. both shunt and compound motor

Question 3

Which D.C. motor is generally preferred for cranes and hoists ?

Accepted Answer

A. Series motor

Question 4

In D.C. machines the residual magnetism is of the order of_________________?

Accepted Answer

A. 2 to 3 per cent

Question 5

For which of the following applications a D.C. motor is preferred over an A.C. motor ?

Accepted Answer

C. Variable speed operation

Question 6

The condition for maximum power in case of D.C. motor is______________?

Accepted Answer

B. back e.m.f. = | x supply voltage

Question 7

The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is______________?

Accepted Answer

D. 0.5

Question 8

Which one of the following is not the function of pole shoes in a D.C. machine ?

Accepted Answer

A. To reduce eddy current loss

Question 9

If the supply voltage for a D.C. motor is increased, which of the following will decrease ?

Accepted Answer

C. Full-load current

Question 10

Which of the following motor is preferred for operation in highly explosive atmosphere ?

Accepted Answer

C. Air motor

Question 11

Sparking at the commutator of a D.C. motor may result in____________?

Accepted Answer

D. all of the above

Question 12

In case of conductively compensated D.C. series motors, the compensating winding is provided______________?

Accepted Answer

C. in series with armature winding

Question 13

For the same H.P. rating and full load speed, following motor has poor starting torque_____________?

Accepted Answer

C. differentially compounded

Question 14

D.C. series motors are used______________?

Accepted Answer

D. in none of the above situations

Question 15

If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens__________?

Accepted Answer

C. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed

Question 16

Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?

Accepted Answer

C. Cumulatively compounded motor

Question 17

Which D.C. motor has got maximum self loading property?

Accepted Answer

D. Differentially compounded motor

Question 18

The power mentioned on the name plate of an electric motor indicates____________?

Accepted Answer

D. the output power available at the shaft

Question 19

The current drawn by the armature of D.C. motor is directly proportional to__________?

Accepted Answer

A. the torque required

Question 20

In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to

Accepted Answer

C. 25% of the previous value