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

Related Mcqs:

1. 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

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. 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

5. All radiations in a black body are___________________?

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

6. Total emissivity of polished silver compared to black body is___________________?

   A. same
   B. higher
   C. more or less same
   D. very much lower
   E. very much higher

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 total emissivity power is .defined as the total amount of radiation emitted by a black body per unit_______________?

   A. temperature
   B. thickness
   C. area
   D. time
   E. area and time

9. According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to____________________?

   A. absolute temperature
   B. T2
   C. T5
   D. t
   E. l/T

10. The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as_________________?

    A. Krichoff’s law
    B. Stefan’s law
    C. Wien’ law
    D. Planck’s law
    E. Black body law