QUIZ-I (Electric Motors)

QUIZ -I

Code:    15EE44                   Subject: Electric motors                                  Semester: IV                       

Date:      03/02/2018            Staff: Prof. Abhinay Gupta

1.    The speed of a DC motor is …..

 directly proportional to back emf

 directly proportional to flux

 inversely proportional to product of flux and back emf

 always constant

2.    As the load on DC shunt motor increased, its speed …..

 increases slightly

 remains constant

 increases proportionately

 reduces slightly

3.     In a dc motor, unidirectional torque is produced with the help of …….

 end plates

 both brushes and commutator

 commutator

 brushes

4.      The starting resistance of DC motor is usually …………..

 200 ohm

 infinitely large

 large

 small

5.     The DC Motor which has approximately constant speed ……

 shunt motor

 cumulatively compound motor

 series motor

 differently compound motor

6.    The output power of an electrical motor is taken from ………………

 the poles

 the conductors

 The armature

 the coupling mounted on shaft

7.    The direction of rotation of DC series motor can be reversed by interchanging ………………

 The supply terminals only

 Both the supply and field terminals

 The field terminals only

8.    The armature current drawn by a dc motor is proportional to …………..

 The speed of the motor

 flux required in the motor

 torque required

 voltage applied to the motor

9.    If the field circuit of a dc shunt motor running at rated speed is open circuited suddenly due to fault, then immateriality thereafter the speed of the motor would tend to ………..

 remain unchanged

 increase

 decrease

 increases excessively

           10.  A dc motor draws high current at the time  of starting because ………..

 Back emf > supply voltage

 back emf < supply voltage

 back emf = 0

 back emf = supply voltage

11. If both the field terminals and armature terminals of the dc shunt motor are interchanged, then ………

 motor will run in same direction

 motor will not run

 motor will run in the opposite direction

 speed of the motor will change

12.  Difference between the no load and full load speeds of a dc shunt motor is of the order of …..

 20%

 5%

 1%

 10%

13. Interpoles in a dc motors are used for ………….

 reduces the sparking at the commutator

 increases the speed of motor

 decreases the counter emf

 converting armature current to dc

14. A brake test on D.C motors is usually restricted to …………….

 small horse power motors

 open frame type motors

 variable speed motors

 high speed motors

15. Which motor is should be used for centrifugal pumps?

 both shunt and series motors

 shunt motor

 Series motor

 compound motor