Question
Thu February 14, 2013 By: Rajarshi Basu

Explain the case of minimum angle deviationand how does it depend upon the angle of incidence and other angles?

Expert Reply
Fri February 15, 2013

Angle of deviation: The angle between the incident ray and the emergent ray is called angle of deviation.

For example: In a prism the angle of deviation is shown.

 

The required relation is, i + e = A + ?

‘i' is the angle of incidence

‘e’ is the angle of emergence

‘A’ is the angle of prism

‘?’ is the angle of deviation

Thus,

? = i + e – A

Thus, angle of deviation depends on i, e and A. Also the deviation depends on the refractive index of the material of the prism.

The Factors affecting the angle of deviation are:

1)Angle of Incidence .

As the angle of incidence increases , first the angle of deviation decreases and becomes minimum for a particular value of angle of incidence then again increases.

2)Angle of Prism.

For a given angle of incidence the angle of deviation increases with increase in the angle of  Prism.

3)Refractive Index of the Prism material.

For a given angle of incidence , the angle of deviation increases with increase in the refractive index of the Prism material.

4)Wave length of Light.

For a given angle of incidence the angle of deviation decreases with in increase of wave length of light.


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