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EEE :: Rectifiers and Converters

  1. The advantage of mercury arc rectifier is that

  2. A.

     it is light in weight and occupies small floor space

    B.

     it has high efficiency

    C.

     it has high overload capacity

    D.

     it is comparatively noiseless

    E.

     all of the above

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  3. The potential drop in the arc, in a mercury arc rectifier, varies

  4. A.

     0.05 V to 0.2 V per cm length of the arc

    B.

     0.5 V to 1.5 V per cm length of the arc

    C.

     2 V to 3.5 V per cm length of the arc

    D.

     none of the above

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  5. In selenium rectifiers efficiencies ranging from ______ to ______ percent are attainable

  6. A.

     25, 35

    B.

     40, 50

    C.

     60, 70

    D.

     75, 85

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  7. The metal rectifiers, as compared to mercury arc rectifiers

  8. A.

     operate on low temperatures

    B.

     can operate on high voltages

    C.

     can operate on heavy loads

    D.

     give poor regulation

    E.

     none of the above

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  9. In a mercury arc rectifier positive ions are attracted towards

  10. A.

     anode

    B.

     cathode

    C.

     shell bottom

    D.

     mercury pool

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  11. The internal efficiency of a mercury arc rectifier depends on

  12. A.

     voltage only

    B.

     current only

    C.

     voltage and current

    D.

     r.m.s. value of current

    E.

     none of the above

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  13. The ignited or auxiliary anode in mercury arc rectifier is made of

  14. A.

     Graphite

    B.

     Boron carbide

    C.

     Aluminium

    D.

     Copper

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  15. The cathdde voltage drop, in a mercury arc rectifier, is due to

  16. A.

     expenditure of energy in ionization

    B.

     surface resistance

    C.

     expenditure of energy in overcoming the electrostatic field

    D.

     expenditure of energy in liberating electrons from the mercury

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  17. In a rotary converter armature currents are

  18. A.

     d.c. only

    B.

     a.c. only

    C.

     partly a.c. and partly d.c.

    D.

     none of the above

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  19. In a mercury arc rectifier______ flow from anode to cathode

  20. A.

     ions

    B.

     electrons

    C.

     ions and electrons

    D.

     any of the above

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