1. The basic operation of an induction motor is based on
(a) self induction.
(b) mutual induction.
(c) magnetic knocking.
(d) Lorentz Force. Answer
2. When the supply frequency of a three phase induction motor is increased, then its synchronous speed is
(a) decreases.
(b) increases.
(c) remain same.
(d) none of the above. Answer
3. In induction motor the unit of slip is
(a) rpm.
(b) metre per second.
(c) radian.
(d) unit less. Answer
4. If a 4-pole 50 Hz 3-phase induction motor run at 1440 rpm, then value of slip is
(a) 0.04%.
(b) 3.3%.
(c) 4%.
(d) 6%. Answer
5. When the rotor of a three phase induction motor is blocked its rotor frequency will become
(a) zero.
(b) half of supply frequency.
(c) equal to supply frequency.
(d) very high. Answer
6. When the rotor of 3 phase induction motor run at synchronous speed, its rotor frequency will become
(a) zero.
(b) half of supply frequency.
(c) equal to supply frequency.
(d) very high. Answer
7. When the rotor of three phase induction motor run at synchronous speed, the value of slip will be
(a) 0.
(b) 0.1.
(c) 0.5.
(d) 1. Answer
8. When the rotor of 3 phase induction motor is blocked, the value of slip will be
(a) zero.
(b) 0.1.
(c) 0.5.
(d) unity. Answer
9. Three phase slip ring induction motor is also known as
(a) controlled motor.
(b) wound rotor motor.
(c) synchronous motor.
(d) series motor. Answer
10. Which DC motor has similar characteristics as a three phase induction motor?
(a) DC shunt motor.
(b) DC series motor.
(c) DC cumulatively compound motor.
(d) DC differentially compound motor. Answer
11. When rotor resistance of a three phase induction motor become equal to its rotor reactance, its starting torque will be
(a) zero.
(b) maximum.
(c) unity.
(d) minimum. Answer
12. When the rotor of three phase induction motor is blocked, its rotor induced emf is
(a) zero.
(b) minimum.
(c) unity.
(d) maximum. Answer
13. The reactance of the rotor circuit of three phase induction motor is maximum at
(a) synchronous speed.
(b) full load.
(c) no load.
(d) stand-still condition. Answer
14. With the increase in supply voltage, the starting torque of a 3 phase induction motor
(a) increases.
(b) decrease.
(c) remains same.
(d) none of the above. Answer
15. If the slip of 3 phase induction motor is increases, the current in its stator winding
(a) increases.
(b) decreases.
(c) remains same.
(d) none of the above. Answer