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Mechanical Engineering :: Heat and Mass Transfer

  1. All radiations in a black body are

  2. A.

     Reflected

    B.

     Refracted

    C.

     Transmitted

    D.

     Absorbed


  3. The heat is transferred by conduction, convection and radiation in

  4. A.

     Melting of ice

    B.

     Boiler furnaces

    C.

     Condensation of steam in condenser

    D.

     None of these


  5. Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in

  6. A.

     Electric heater

    B.

     Steam condenser

    C.

     Boiler

    D.

     Refrigerator condenser coils


  7. The radiation emitted by a black body is known as

  8. A.

     Black radiation

    B.

     Full radiation

    C.

     Total radiation

    D.

     All of these


  9. The amount of heat flow through a body by conduction is

  10. A.

     Directly proportional to the surface area of the body

    B.

     Directly proportional to the temperature difference on the two faces of the body

    C.

     Dependent upon the material of the body

    D.

     All of the above


  11. The emissive power of a body depends upon its

  12. A.

     Temperature

    B.

     Wave length

    C.

     Physical nature

    D.

     All of the above


  13. The amount of radiation mainly depends upon the

  14. A.

     Nature of the body

    B.

     Temperature of the body

    C.

     Type of surface of the body

    D.

     All of these


  15. Film coefficient is defined as Inside diameter of tube

  16. A.

     Equivalent thickness of film

    B.

     Thermal conductivity Equivalent thickness of film Specific heat × Viscosity

    C.

     Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity

    D.

     Film coefficient × Inside diameter Thermal conductivity


  17. Thermal diffusivity is a

  18. A.

     Function of temperature

    B.

     Physical property of a substance

    C.

     Dimensionless parameter

    D.

     All of these


  19. The most commonly used method for the design of duct size is the

  20. A.

     Velocity reduction method

    B.

     Equal friction method

    C.

     Static regains method

    D.

     Dual or double method