A body is called grey if the monochromatic emissivity of the body is___________________?

Related Mcqs:

1. 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...

2. While the total emissivity of a perfect black body is unity, the same for a real body is__________________?

   A. 0 B. 1 C. > 1 D. Between 0 and 1...

3. Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be_________________?

   A. 0.35 B. 0.45 C. 0.55 D. 0.85...

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 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...

6. What is the emissivity of a black body ?

   A. 0 B. 1 C. 0.5 D. 0.90...

7. 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...

8. With increase in temperature, the total emissivity of conductors____________________?

   A. Increases B. Decreases C. Remain same D. Decreases linearly...

9. The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by__________________?

   A. Painting the surface black B. Painting the surface white (with aluminium paint) C. Giving the surface a mirror finish D. Roughening the surface...

10. A _____________ surface has the maximum thermal emissivity out of the following ?

    A. Black & smooth B. Black & rough C. White & smooth D. White & rough...