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A light ray incidents normally on one su...

A light ray incidents normally on one surface of an equilateral prism. The angle of deviation of the light ray is (refractive index of the material of the prism =`sqrt(2)`)

A

`60^(@)`

B

`30^(@)`

C

`0^(@)`

D

`120^(@)`

Text Solution

Verified by Experts

The correct Answer is:
A
Given, `i=0^(@)`
So, `(sin i)/(sin r_(1))=sqrt(2)`
`(sin 0^(@))/(sin r_(1))=sqrt(2)`
`sin r_(1) =0" or "r_(1)=0`
Now, `(sin r_(2))/(sin e) =(1)/(mu)`
`rArr sin e = sqrt(2) sin r_(2)`
But, `r_(1)+r_(2)=60^(@)`
So, `sin e =sqrt(2) sin 60^(@)`
`=sqrt(2)xxsqrt(3)//2gt1`
So, light is incidenting at more than critical angle and totally internally reflected.
`therefore` Deviation angle `=(i+e)-(r_(1)+r_(2))`
`=0-60^(@)=60^(@)` (in magnitude)
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