MULTIPLE CHOICE QUESTIONS
Q.1 Regenerative braking
(A)
Can be used for stopping a motor.
(B)
Cannot be easily applied to DC series motors.
(C)
Can be easily applied to DC shunt motors
(D)
Cannot be used when motor load has overhauling characteristics.
Q.2 If the field circuits of an unloaded salient
pole synchronous motor gets suddenly
open
circuited,
then
(A)
The motor stops.
(B)
It continues to run at the same speed.
(C)
Its runs at the slower speed.
(D)
It runs at a very high speed.
Q.3 No load current in a transformer:
(A)
lags the applied voltage by 90°
(B)
lags the applied voltage by somewhat less than 90°
(C)
leads the applied voltage by 90°
(D)
leads the applied voltage by somewhat less than 90°
Q.4 The armature of a dc machine is laminated to
reduce:
(A)
Eddy current loss
(B) Hysteresis loss
(C)
copper losses
(D) friction and windage losses
Q.5 A single phase Hysteresis motor
(A)
can run at synchronous speed only
(B)
can run at sub synchronous speed only
(C)
can run at synchronous and super
synchronous speed
(D) can run at synchronous and sub synchronous speed
Q.6 The direction of rotation of a hysteresis motor is
determined by the
(A) retentivity of the rotor material
(B) amount of hysteresis loss
(C) permeability of rotor material
(D) position of shaded pole with respect to the main
pole.
Q.7 Speed of the universal motor is
(A) dependent on frequency of supply
(B) proportional to frequency of supply
(C) independent of frequency of supply
(D) none of the above.
Q.8 In the shaded pole squirrel cage induction motor
the flux in the shaded part always
(A) leads the flux in the unshaded pole segment
(B) is in phase with the flux in the unshaded pole
segment
(C) lags the flux in the unshaded pole segment
(D) none of the above.
Q.9 Which of the following motor is an interesting
example of beneficially utilizing a phenomenon that is often considered
undesirable ?
(A) hysteresis motor
(B) reluctance motor
(C) stepper motor
(D) shaded-pole motor.
Q.10 Usually, large motors are more efficient than
small ones. The efficiency of the tiny motor used in a wrist watch is
approximately.......... per cent.
(A) 1
(B) 10
(C) 50
(D) 80
