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EEE :: D.C. Generators

  1. A series generator can self-excite

  2. A.

     Only if the load current is zero

    B.

     Only if the load current is not zero

    C.

     Irrespective of the value of load current

    D.

     None of the above

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  3. The armature of D.C. generator is laminated to

  4. A.

     reduce the bulk

    B.

     provide the bulk

    C.

     insulate the core

    D.

     reduce eddy current loss

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  5. The material for commutator brushes is generally

  6. A.

     Mica

    B.

     Copper

    C.

     Cast iron

    D.

     Carbon

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  7. Armature coil is short circuited by brushes when it lies

  8. A.

     Along neutral axis

    B.

     Along field axis

    C.

     In any of the above positions

    D.

     In none of the above positions

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  9. Satisfactory commutation of D.C. machines requires

  10. A.

     Brushes should be of proper grade and size

    B.

     Brushes should smoothly run in the holders

    C.

     Smooth, concentric commutator properly undercut

    D.

     All of the above

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  11. A D.C. generator can be considered as

  12. A.

     Rectifier

    B.

     Prime mover

    C.

     Rotating amplifier

    D.

     Power pump

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  13. In case of a flat compounded generator

  14. A.

     Voltage generated is less than the rated voltage

    B.

     Generated voltage is proportional to the load on the generator

    C.

     Voltage remains constant irrespective of the load

    D.

     Speed varies in proportion to the load on the generator

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  15. The e.m.f. generated in a D.C. generator is directly proportional to

  16. A.

     Flux/pole

    B.

     Speed of armature

    C.

     Number of poles

    D.

     All of the above

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  17. A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be

  18. A.

     Zero

    B.

     About 2 V

    C.

     About 50 V

    D.

     220 V

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  19. If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by

  20. A.

     Blv

    B.

     Blv²

    C.

     Bl²v

    D.

     Bl²v²

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