Heat Transfer Mock Test 5

1. The fraction of the radiative energy that is diffused from one surface element and strikes the other surface directly with no intervening reflections is called
(i) Radiation shape factor
(ii) Geometrical factor
(iii) Configuration factor
Choose the correct answer

2. For the same type of shapes, the value of the radiation shape factor will be higher when

3. A 100 W light bulb has a tungsten filament (emissivity = 0.30) which is required to operate at 2780 K. If the bulb is completely evacuated, calculate the minimum surface area of the tungsten filament

4. A small black body has a total emissive power of 4.5 k W/m². In which range of the spectrum does this wavelength fall?

5. A small body has a total emissive power of 4.5 kW/m². Determine its surface temperature of maximum emission

6. Spatial distribution is also known as directional distribution.

7. If radiant energy E _B emitted by the black surface strikes the non-black surface. If non-black surface has absorptivity α, it will absorb how much radiations?

8. If a black body at 1000 K and a gray body at 1250 K emit the same amount of radiation, what should be the emissivity of the gray body?

9. The intensity of normal radiation I _n is how much times the emissive power?

10. A black body of 0.2 m² area has an effective temperature of 800 K. Calculate the intensity of normal radiations