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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


  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


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

  6. A.

     Natural graphite

    B.

     Hard carbon

    C.

     Electro graphitic

    D.

     Metal graphite


  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


  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


  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


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

  14. A.

     2

    B.

     3

    C.

     5

    D.

     7


  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


  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


  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