Single Phase Motor MCQ

1. Which motor is preferred in electric shavers?

  1. Shaded pole motor
  2. Hysteresis motor
  3. Reluctance motor
  4. Universal motor

Answer. d

2. In a single-phase induction motor, the starting torque developed is proportional to

  1. supply voltage
  2. (supply voltage)2
  3. 1/(supply voltage)2
  4. 1/(supply voltage)

Answer. b

3. Which of the following motor is suitable for frequent starting and stopping?

  1. Capacitor start motor
  2. Capacitor start capacitor run motor
  3. Resistance split phase motor
  4. All of the above

Answer. a

4. Reluctance torque in rotating machines is present when

  1. air-gap is not uniform.
  2. reluctance seen by rotor m.m.f. is constant.
  3. reluctance seen by rotor m.m.f. varies.
  4. none of these

Answer. c

5. The repulsion motor starts and runs as a

  1. split-phase motor
  2. capacitor-start motor
  3. repulsion motor
  4. compound motor

Answer. c

6. A repulsion start induction-run motor runs as an induction motor when the

  1. commutator segments are short-circuited
  2. brushes are shifted to a neutral plane
  3. shorting devices are disconnected
  4. stator connections are reversed

Answer. a

7. Before a capacitor-start motor can reverse its direction of rotation the

  1. centrifugal switch must be opened
  2. running winding must be opened
  3. starting winding must be connected to the line
  4. capacitor connections must be changed

Answer. c

8. As compared to a split-phase motor, a capacitor start motor has …….

  1. higher starting torque
  2. lower starting torque
  3. higher running torque
  4. None of these

Answer. a

9. The commutator in a repulsion motor provides

  1. armature windings
  2. stator windings
  3. short-circuiting device
  4. starting-winding

Answer. a

10. The m.m.f. produced by a single-phase winding is

  1. Pulsating and stationary
  2. Pulsating and rotating
  3. Constant in amplitude and stationary
  4. Constant in amplitude and rotating

Answer. a

11. Which of the following motors is most suitable for signalling devices and timer?

  1. D.C. series motor
  2. D.C. shunt motor
  3. Two phase induction motor
  4. Reluctance motor

Answer. d

12. The squirrel-cage winding of a single-phase motor is placed in the

  1. Armature
  2. Stator
  3. Rotor
  4. Field

Answer. c

13. Which of the following is the most economical method for starting single-phase motor?

  1. Capacitor start method
  2. Split-phase method
  3. Induction-start method
  4. Resistance-start method

Answer. a

14. The value of the capacitor in a capacitor start motor controls the

  1. Starting torque
  2. Speed of the motor
  3. Efficiency
  4. None of these

Answer. a

15. The speed of the rotating magnetic field in an induction motor is known as the

  1. Slip speed
  2. Effective speed
  3. Shaft speed
  4. Synchronous speed

Answer. d

16. The universal motor speed can be controlled by

  1. Centrifugal mechanism only
  2. Resistance method only
  3. Anyone of the given three methods
  4. Tapped field method only

Answer. c

17. In a single-phase induction motor the stator winding produces a flux which is

  1. alternating
  2. alternating and rotating
  3. rotating
  4. constant everywhere

Answer. a

18. A universal motor may be operated by

  1. Only dc supply
  2. Only ac supply
  3. Neither dc nor ac supply
  4. Both dc supply and ac supply

Answer. d

19. For starting a single-phase induction motor the auxiliary winding and the main winding are spaced apart by

  1. 270°
  2. 90°
  3. 180°

Answer. b

20. The torque in a single-phase motor is given by

  1. backward torque
  2. forward torque
  3. forward torque − backward torque
  4. forward torque + backward torque

Answer. d

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