Question

When a glass prism of refractive angle 60 degree is immersed in a liquid its angle of minimum deviation is 30 degree the critical angle of glass with respect to the liquid medium is?

Answer 1

hello friend..!!

• according to the question, we should calculate the critical angle of glass with respect to liquid.


• given that, A = 60 , d = 30 .

we know,

$\beta = ( \frac{sin( \frac{1}{2}(a + d)) }{sin \frac{1}{2}a } )$

implies ,

sin ( 60 + 30 / 2 ) / sin ( 60/2)

implies,

β = sin 45 / sin 30

β = √2


implies,

1 / sin i(c) = √2

therefore,

sin i(c) = 1/ √2

implies that the critical angle is of 45 degree.


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Hope it is useful...!!