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ECE :: Electromagnetic Induction

  1. Increasing the field or increasing the current will decrease the force on the conductor.

  2. A.

     Yes

    B.

     No


  3. A moving magnetic field will produce the same effect as a conductor that is moving.

  4. A.

     True

    B.

     False


  5. Which of the fpllowing inductor will have the least eddy current losses ?

  6. A.

     Air core

    B.

     Laminated iron core

    C.

     Iron core

    D.

     Powdered iron core


  7. A 500 turns solenoid develops an average induced voltage of 60 V. Over what time interval must a flux change of 0.06 Wb occur to produce such a voltage?

  8. A.

     0.01 s

    B.

     0.1 s

    C.

     0.5 s

    D.


  9. A coil with negligible resistance has 50V across it with 10 mA. The inductive reactance is

  10. A.

     50 ohms

    B.

     500 ohms

    C.

     1000 ohms

    D.

     5000 ohms


  11. For a purely inductive circuit which of the following is true?

  12. A.

     Apparent power is zero

    B.

     Relative power is zero

    C.

     Actual power of the circuit is zero

    D.

     Any capacitance even if present in the circuit will not be charged


  13. The core of a coil has a length of 200 mm. The inductance of coil is 6 mH. If the core length is doubled, all other quantities, remaining the same, the inductance will be

  14. A.

     3 mH

    B.

     12 mH

    C.

     24 mH

    D.

     48 mH


  15. A 200 turn coil has an inductance of 12 mH. If the number of turns is increased to 400 turns, all other quantities (area, length etc.) remaining the same, the inductance will be

  16. A.

     6 mH

    B.

     146 mH

    C.

     24 mH

    D.

     48 mH


  17. An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be

  18. A.

     64 A/s

    B.

     32 A/s

    C.

     16 A/s

    D.

     4 A/s


  19. Which of the following circuit element stores energy in the electromagnetic field?

  20. A.

     Inductance

    B.

     Condenser

    C.

     Variable resistor

    D.

     Resistance