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EEE :: Heating and Welding

  1. Radiations from a black body are proportional to

  2. A.

     T

    B.

     T2

    C.

     T3

    D.

     T4


  3. Properly of low temperature co-eflficient of heating element is desired due to which of the following reasons?

  4. A.

     To avoid initial rush of current

    B.

     To avoid change in kW rating with temperature

    C.

     Both (A) and (B)

    D.

     Either (A) or (B)


  5. The material of the heating element for a furnace should have

  6. A.

     Lower melting point

    B.

     Higher temperature coefficient

    C.

     High specific resistance

    D.

     All of the above


  7. In induction heating __________ is abnormally high.

  8. A.

     Phase angle

    B.

     Frequency

    C.

     Current

    D.

     Voltage


  9. For the transmission of heat from one body to another

  10. A.

     Temperature of the two bodies must be different

    B.

     Both bodies must be solids

    C.

     Both bodies must be in contact

    D.

     At least one of the bodies must have some source of heating


  11. When a body reflects entire radiation incident on it, then it is known as

  12. A.

     White body

    B.

     Grey body

    C.

     Black body

    D.

     Transparent body


  13. Heat transfer by condition will not occur when

  14. A.

     Bodies are kept in vacuum

    B.

     Bodies are immersed in water

    C.

     Bodies are exposed to thermal radiations

    D.

     Temperatures of the two bodies are identical


  15. A perfect black body is one that

  16. A.

     Transmits all incident radiations

    B.

     Absorbs all incident radiations

    C.

     Reflects all incident radiations

    D.

     Absorbs, reflects and transmits all incident radiations


  17. For heating element high resistivity material is chosen to

  18. A.

     Reduce the length of heating element

    B.

     Increase the life of the heating element

    C.

     Reduce the effect of oxidation

    D.

     Produce large amount of heat


  19. Which of the following heating methods has maximum power factor?

  20. A.

     Arc heating

    B.

     Dielectric heating

    C.

     Induction heating

    D.

     Resistance heating