The practical illustration of the phenomenon of mutual induction is____________?

Related Mcqs:

1. A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is____________________?

   A. slop speed operation
   B. high starting torque
   C. low windage losses
   D. all of the above

2. The self inductances of two coils are 8 mH and 18 mH. If the co-efficients of coupling is 0.5, the mutual inductance of the coils is______________?

   A. 4 mH
   B. 5 mH
   C. 6 mH
   D. 12 mH

3. Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. If the two coils are connected in series, the total inductance will be_____________?

   A. 6 H
   B. 8 H
   C. 12 H
   D. 24 H

4. Two 300 uH coils in series without mutual coupling have a total inductance of___________?

   A. 300 uH
   B. 600 uH
   C. 150 uH
   D. 75 uH

5. As per Faraday’s laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it_______________?

   A. lies perpendicular to the magnetic flux
   B. lies in a magnetic field
   C. cuts magnetic flux
   D. moves parallel to the direction of the magnetic field

6. For three-phase induction motors which of the following is the least efficient method of speed control ?

   A. Cascade control
   B. Pole changing
   C. Rheostat control
   D. Combination of cascade and pole changing

7. _________________method of starting a three phase induction motor needs six terminals ?

   A. Star-delta
   B. Resistance starting
   C. Auto-transformer
   D. None of the above

8. In squirrel cage induction motors which of the following methods of starting cannot be used ?

   A. Resistance in rotor circuit
   B. Resistance in stator circuit
   C. Auto-transformer starting
   D. Star-delta starting

9. In ________________ method of staging three phase induction motors the starting voltage is not reduced?

   A. auto-transformer
   B. star-delta
   C. slip ring
   D. any of the above

10. The cost of an induction motor will increase as________________?

    A. horsepower rating increases but r.p.m. decreases
    B. horsepower rating decreases but r.p.m. increases
    C. horsepower rating and operating speed increases
    D. horsepower rating and operating speed decreases