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

Related Mcqs:

1. Depending on the radiating properties, a body will be black 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 = 0
   E. a = 0,x + p= 1.
   where a = absorptivity, p == reflectivity, X = transmissivity

2. 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

3. Depending on the radiating properties, a body will be opaque when _________________?

   A. p = 0, x = 0 and a = 1
   B. p=l,x = 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

4. 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

5. 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

6. 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

7. All radiations in a black body are___________________?

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

8. 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

9. Absorptivity of a body will be equal to its emissivity___________________?

   A. at all temperatures
   B. at one particular temperature
   C. when system is under thermal equi-librium
   D. at critical temperature
   E. for a polished body

10. 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