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ECE :: Electromagnetic Induction

  1. Which of the following inductor will have the least eddy current losses?

  2. A.

     Air core

    B.

     Laminated iron core

    C.

     Iron core

    D.

     Powdered iron core


  3. Find the force acting on a conductor 3m long carrying a current of 50 amperes at right angles to a magnetic field having a flux density of 0.67 tesla

  4. A.

     100 N

    B.

     400 N

    C.

     600 N

    D.

     1000 N


  5. Both the number of turns and the core length of an inductive coil are doubled. Its self-inductance will be

  6. A.

     Unaffected

    B.

     Doubled

    C.

     Halved

    D.

     Quadrupled


  7. The polarity of the induced voltage can be determined by using the left-hand generator rule.

  8. A.

     Yes

    B.

     No


  9. A conductor 2 meters long moves at right angles to a magnetic field of flux density 1 tesla with a velocity of 12.5 m/s. The induced e.m.f. in the conductor will be

  10. A.

     10 V

    B.

     15 V

    C.

     25 V

    D.

     50 V


  11. If current in a conductor increases then according to Lenz's law self-induced voltage will

  12. A.

     Aid the increasing current

    B.

     Tend to decrease the amount of current

    C.

     Produce current opposite to the increasing current

    D.

     Aid the applied voltage


  13. Two coils have inductances of 8 mH and 18 mH and a coefficient of coupling of 0.5. If the two coils are connected in series aiding, the total inductance will be

  14. A.

     32 mH

    B.

     38 mH

    C.

     40 mH

    D.

     48 mH


  15. 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

  16. A.

     6 H

    B.

     8 H

    C.

     12 H

    D.

     24 H


  17. A coil is wound on iron core which carries current I. The self-induced voltage in the coil is not affected by

  18. A.

     Variation in coil current

    B.

     Variation in voltage to the coil

    C.

     Change of number of turns of coil

    D.

     The resistance of magnetic path


  19. Mutually inductance between two magnetically coupled coils depends on

  20. A.

     Permeability of the core

    B.

     The number of their turns

    C.

     Cross-sectional area of their common core

    D.

     All of the above