A grey body is one whose absorptivity_________________?

Related Mcqs:

1. A grey body is one whose absorptivity _________________?

   A. varies with temperature
   B. varies with the wave length of incident ray
   C. varies with both
   D. does not vary with temperature and wave length of the incident ray
   E. there is no such criterion

2. When heat is transferred form hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by __________________?

   A. conduction
   B. convection
   C. radiation
   D. conduction and convection
   E. convection and radiation

3. Emissivity of a white polished body in comparison to a black body is________________?

   A. higher
   B. lower
   C. same
   D. depends upon the shape of body
   E. none of the above

4. 40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is____________________?

   A. 0.45
   B. 0.55
   C. 0.40
   D. 0.75
   E. 0.60

5. All radiations in a black body are___________________?

   A. reflected
   B. refracted
   C. transmitted
   D. absorbed
   E. partly reflected and partly absorbed

6. Depending on the radiating properties, body will be transparent when________________?

   A. p = 0, x = 0 and a = 1
   B. p=l,x = 0,anda = 0
   C. p = 0, T= l,anda = 0
   D. X = 0, a + p = 1
   E. a = 0,x + p= 1

7. A perfect black body is one which_______________?

   A. is black in colour
   B. reflects all heat
   C. transmits all heat radiations
   D. abslprbs heat radiations of all wave lengths falling on it
   E. fully opaque

8. The ratio of the energy absorbed by the body to total energy falling on it is called_________________?

   A. absorptive power
   B. emissive power
   C. absorptivity
   D. emissivity
   E. none of the above

9. The emissive power of a body depends upon its___________________?

   A. temperature
   B. wave length
   C. physical nature
   D. all of the above
   E. none of the above

10. Depending on the radiating properties, a body will be white when_________________?

    A. p = 0, x = 0 and a = 1
    B. p=l,T = 0anda = 0
    C. p = 0, x = 1 and a = 0
    D. x = 0, a + p = 1
    E. a = 0, x + p = 1.

    where a = absorptivity, p = reflectivity, x = transmissivity