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EEE :: Electrical Machine Design

  1. A current density of _________ is used for large power transformers with forced circulation of oil or with water cooling coils

  2. A.

     1.5 to 2.5 A/mm²

    B.

     3.5 to 4.5 A/mm²

    C.

     4.0 to 5.0 A/mm²

    D.

     5.4 to 6.2 A/mm²

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  3. The resistance in the circuit of the moving coil of a dynamometer wattmeter should be

  4. A.

     almost zero

    B.

     low

    C.

     high

    D.

     none of the above

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  5. _______ brushes are fragile and cause excessive wear of commutator,

  6. A.

     Natural graphite

    B.

     Hard carbon

    C.

     Electro graphitic

    D.

     Metal graphite

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  7. To avoid the effect of stray magnetic field in A.C. bridges we can use

  8. A.

     magnetic screening

    B.

     Wagner earthing device

    C.

     wave filters

    D.

     any of the above

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  9. It is required to measure the true open circuit e.m.f. of a battery. The best device is

  10. A.

     D.C. voltmeter

    B.

     Ammeter and a known resistance

    C.

     D.'potentiometer

    D.

     None of the above

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  11. Hydrogen has a heat transfer co-efficient _____ times that of air

  12. A.

     1.5

    B.

     2.5

    C.

     3.5

    D.

     4.5

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  13. The thermal conductivity of hydrogen is ______ times that of air

  14. A.

     2

    B.

     3

    C.

     5

    D.

     7

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  15. The design of mechanical parts is particularly important in case of _____ speed machines.

  16. A.

     low

    B.

     medium

    C.

     high

    D.

     any of the above

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  17. A voltage of about 200 V can be measured

  18. A.

     directly by a D.C. potentiometer

    B.

     a D.C. potentiometer in conjunction with a volt ratio box

    C.

     a D.C. potentiometer in conjunction with a known resistance

    D.

     none of the above

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  19. Which of the following is measured by using a vector voltmeter ?

  20. A.

     Amplifier gain and phase shift

    B.

     Filler transfer functions

    C.

     Complex insersion loss

    D.

     All of the above

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