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 reduces to zero and then again increase
D. the intensity increases continuously

Answer

C

Explanation

Here Angle of incidence, `i` = 57
`tan57^(@)=1.54`
`u_("glass")=tani`
It means, Here Breswster.s law is followed and the reflected ray is completely polarised.
Now, when reflected ray is analysed through a polaroid then intensity of light is given by malus law.
i.e. `I=I_(0)cos^(2)theta`
on rotating polaroid `.theta.` changes. Due to which intensity first decreases and then increases.