concept of different bodies

this is for transparent body , opaque body , white body , black body

1. Name:
I.Patel vaibhav
II.Patel devang
III.Parmar hiren
IV.Himanshu olkiya
V.Bhalodiya jenish

Subject : Heat transfer

2. Concept Of Different Bodies

3. Black Body:
a black body is an object that absorbs all the radiant energy
reaching its surface from all the direction with all the with all the
wavelengths. it is perfect absorbing body.

4. Blackbody Radiation
i.The characteristics of a blackbody are :
ii.It is a perfect emitter.
iii.At any prescribed temperature it has the highest
monochromatic emissive power at all wave lengths.
iv.A blackbody absorbs all the incident energy and there fore
A = a
l
= 1.
v.It is non reflective body (t=0).
vi.It is opaque (t = 0).
vii.It is a diffuse emitter

5. White body:
If all the incident radiation falling on the body are
reflected , it is called a white body .

6. Gray body:
A gray body is defined as a body whose absorptivity of a
surface does not vary with variation in temperature and
wavelength of the incident radiation.

8. Opaque body:
When no irradiation is transmitted through the body, it
is called ‘opaque body’ .
Examples : all the thick metallic and non-
metalic surface , all liquids, etc.

9. Transparent body:
When all the irradiation is transmitted through the
body, it is called transparent body.
For transparent body : a = 0 , p = 0 , t = 1
For example : dry air

10. Regular and diffuse reflection
Regular reflection:
If the angle between the reflected beam and normal to the
surface equals the angle made by the irradiation with the same
normal then it is called regular or specular or highly polished
one.

11. Diffused reflection :
In this case, the incident radiation beam is reflected in all the
directions.
The reflection from real surface is neither diffused nor regular but
combination of above two and its specular behaviour is shown in
figure.

12. Thank you