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Radiation-:-Processes-and-Properties

1. The absorptivity of a surface depends upon
(i) Direction of reflected radiation
(ii) Temperature of surface
(iii) Composition
Identify correct statements


Hint Answer

2. Thermal radiations occur in portion of electromagnetic spectrum between wavelengths


Hint Answer

3. Spatial distribution is also known as directional distribution.


Hint Answer

4. The value of radiation coefficient or Stefan-Boltzmann constant is


Hint Answer

5. A polished metal pipe 5 cm outside diameter and 370 K temperature at outer surface is exposed to ambient conditions at 295 K temperature. The emissivity of surface is 0.2 and convection coefficient of heat transfer is 11.35 W/m2 degree. Calculate overall coefficient of heat transfer by combined mode of convection and radiation


Hint Answer

6. In given diagram let r be length of line of propagation between radiating and incident surfaces. What is value of solid angle W?
In given diagram let r be length of line of propagation between radiating and incident surfaces. What is value of solid angle W?\r\n


Hint Answer

7. Let 220 W/m2 of radiant energy is absorbed by a convex surface, 90 W/m2 is reflected and 40 W/m2 is transmitted through it. What is value of absorptivity?


Hint Answer

8. What is wavelength band for solar radiation?


Hint Answer

9. What is wavelength band of gamma rays?


Hint Answer

10. Isormal furnaces, with small apertures, approximate a black body and are frequently used to calibrate heat flux gauges.


Hint Answer

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This Chapter Radiation-:-Processes-and-Properties consists of the following topics

Radiation : Processes and Properties

The absorptivity of a surface depends upon
(i) Direction of reflected radiation
(ii) Temperature of surface
(iii) Composition
Identify correct statements

;

Thermal radiations occur in portion of electromagnetic spectrum between wavelengths

;

Spatial distribution is also known as directional distribution.

;

The value of radiation coefficient or Stefan-Boltzmann constant is

;

A polished metal pipe 5 cm outside diameter and 370 K temperature at outer surface is exposed to ambient conditions at 295 K temperature. The emissivity of surface is 0.2 and convection coefficient of heat transfer is 11.35 W/m2 degree. Calculate overall coefficient of heat transfer by combined mode of convection and radiation

;

In given diagram let r be length of line of propagation between radiating and incident surfaces. What is value of solid angle W?
In given diagram let r be length of line of propagation between radiating and incident surfaces. What is value of solid angle W?\r\n

;

Let 220 W/m2 of radiant energy is absorbed by a convex surface, 90 W/m2 is reflected and 40 W/m2 is transmitted through it. What is value of absorptivity?

;

What is wavelength band for solar radiation?

;

What is wavelength band of gamma rays?

;

Isormal furnaces, with small apertures, approximate a black body and are frequently used to calibrate heat flux gauges.

;