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

Related Mcqs:

1. 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...

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

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

3. 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...

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

   A. Zero B. Unity C. Same for all wavelengths D. Different for all wavelengths...

5. 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...

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. 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...

8. What is the absorptivity of a black body?

   A. 1 B. 0 C. 0.78 D. 0.95...

9. 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...

10. 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...