A beam of light is incident on a glass slab `(mu = 1.54)` in a direction as shown in the figure. The reflected light is analysed by a polaroid prism. On rotating the polaroid, `(tan 57^(@) = 1.54)`
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Options

A. the intensity remains unchanged
B. the intensity is reduced to zero and remains at zero
C. the intensity gradually reduced to zero and then again increases
D. the intensity increase continously

Answer

C

Explanation

Given, `mu=1.54`
We know that `theta=tan^(-1)(u)`
`theta=tan^(-1)(1.54) Rightarrow theta=57^(@)`
On rotatin the polyroid the reflected light is fully polarised. Here the intensity gradually reduces to zero and then again increases.