“The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium”. This is ______________ law?

Related Mcqs:

1. The ratio of total radiating power to the absorptivity of the body depends upon the _____________ as per Kirchoff‟s law?

   A. Wavelength of radiation
   B. Nature of the body
   C. Temperature of the body
   D. None of these

2. As per Kirchoff‟s law, the ratio of the total radiating power to the absorptivity of a body depends on the_______________?

   A. Temperature of the body only
   B. Wavelength of monochromatic radiation
   C. Both A. and B.
   D. Nature of material of body

3. Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ?

   A. Aluminium foil
   B. Refractory bricks
   C. Iron plate
   D. Coke breeze

4. Which one gives the monochromatic emissive power for black body radiation ?

   A. Planck’s law
   B. Kirchhoff’s law
   C. Wien’s law
   D. Stefan-Boltzmann law

5. The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)?

   A. αT
   B. α × 1/T
   C. α T4
   D. Independent of T

6. The absorptivity of a grey body at a given temperature _____________ with increasing wavelength of radiation?

   A. Increases
   B. Decreases
   C. Remain constant
   D. May increase or decrease; depends on the material

7. The absorptivity of a body is equal to its emissivity _________________?

   A. At a particular temperature
   B. For circular bodies
   C. Under thermal equilibrium
   D. None of these

8. Absorptivity and reflectivity of a perfect black body are respectively _______________?

   A. 1 and 0
   B. 0 and 1
   C. 1 and ∞
   D. 0 and 0.5

9. Which of the following has the minimum absorptivity ?

   A. Aluminium foil
   B. Coal dust
   C. Refractory bricks
   D. Iron plates

10. The sum of reflectivity and absorptivity for an opaque body is equal to____________________?

    A. 0.5
    B. 1
    C. 0
    D. 2