The electric motor used in portable drills is__________?
(A) capacitor run motor
(B) hysteresis motor
(C) universal motor
(D) repulsion motor
In a hysteresis motor, the rotor must have____________?
(A) retentivity
(B) resistivity
(C) susceptibility
(D) none of the above
Locked rotor current of a shaded pole motor is____________?
(A) equal to full load current
(B) less than full load current
(C) slightly more than full load current
(D) several times the full load current
Which of the following statements regarding repulsion-start induction motor is incorrect ?
(A) It requires more maintenance of commutator and other mechanical devices
(B) It makes quite a bit of noise on starting
(C) In fractional horse power motors, it has replaced the capacitor motors
(D) It is not easily reversed
After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on ______________?
(A) running winding
(B) rotor winding
(C) field winding
(D) compensating winding
A.C. series motor as compared to D.C. series motor has__________?
(A) smaller brush width
(B) less number of field turns
(C) more number of armature turns
(D) less air gap
(D) all of the above
Hysteresis motor is particularly useful for high-quality record players and tape-recorders because___________?
(A) it revolves synchronously
(B) it is not subject to any magnetic or mechanical vibrations
(C) it can be easily manufactured in extremely small sizes of up to 1 W output
(D) it develops hysteresis torque which is extremely steady both in amplitude and phase
Which of the following statements regarding single-phase induction motors correct?
(A) It requires only one winding
(B) It can rotate in one direction only
(C) It is self-starting
(D) It is not self-starting
Speed control of a universal motor is achieved by__________?
(A) varying field flux with tapped field windings
(B) connecting rheostat in series
(C) applying variable voltage by means of silicon controlled rectifier
(D) applying variable voltage by means of variable auto-transformer
(D) all of the above methods
Which of the following statements regarding hysteresis motor is in incorrect?
(A) It is extremely sensitive to fluctuations in supply voltage
(B) Its high starting torque is due to its high rotor hysteresis loss
(C) It is extremely quiet in operation
(D) It accelerates from rest to full-speed almost instantaneously