DC Motors Quiz practies questions test1

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1. In D.C. shunt motors as load is reduced _____.
the speed will increase abruptly	the speed will increase in proportion to reduction in load
the speed will remain almost/constant	the speed will reduce

2. A D.C. series motor is that which _____.
has its field winding consisting of thick wire and less turns	has a poor torque
can be started easily without load	has almost constant speed

3. For starting a D.C. motor a starter is required because _____.
it limits the speed of the motor	it limits the starting current to a safe value
it starts the motor	none of the above

4. The type of D.C. motor used for shears and punches is ______.
shunt motor	series motor
differential compoutid D.C. motor	cumulative compound D.C. motor

5. If a D.C. motor is connected across the A.C. supply it will _____.
run at normal speed	not run
run at lower speed	burn due to heat produced in the field winding by .eddy currents

6. To get the speed of D.C, motor below the normal without wastage of electrical energy is used.
Ward Leonard control	rheostatic control
any of the above method	none of the above method

7. When two D.C. series motors are connected in parallel, the resultant speed is _____.
more than the normal speed	loss than the normal speed
normal speed	zero

8. The speed of a D.C. shunt motor more than its full-load speed can be obtained by _____.
decreasing the field current	increasing the field current
decreasing the armature current	increasing the armature current

9. In a D.C. shunt motor, speed is _______.
independent of armature current	directly proportional to the armature current
proportional to the square of the current	inversely proportional to the armature current

10. A direct on line starter is used: for starting motors
up to 5 H.P.	up to 10 H.P.
up to 15 H.P.	up to 20 H.P.

11. What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
The motor will stop	The motor will continue to run
The armature may burn	The motor will run noisy

12. In case of D.C. shunt motors the speed is dependent on back e.m.f. only because _____.
back e.m.f. is equal to armature drop	armature drop is negligible
flux is proportional to armature current	flux is practically constant in D:C. shunt motors

13. In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be ______.
almost negligible	rated full-load current
less than full-load current	more than full-load current

14. These days D.C. motors are widely used in ______.
pumping sets	air compressors
electric traction	machine shops

15. By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?
Frame	Shaft
Commutator	Stator

16. In which of the following applications D.C. series motor is invariably tried?
Starter for a car	Drive for a water pump
Fan motor	Motor operation in A.C. or D.C.

17. In D.C. machines fractional pitch winding is used _____.
to improve cooling	to reduce copper losses
to increase the generated e.m.f.	to reduce the sparking

18. A three point starter is considered suitable for ______.
shunt motors	shunt as well as compound motors
shunt, compound and series motors	all D.C. motors

19. In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be ______.
100%	around 90%
anywhere between 75% and 90%	less than 50%

20. The ratio of starting torque to full-load torque is least in case of ______.
series motors	shunt motors
compound motors	none of the above