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# A ray of light is incident on a rectangular glass block at $45^{\circ}$ on glass- air interface. The refractive index of glass is $\sqrt 2$. Then

(a) The ray will emerge back into air without deviation

(b) will be reflected back into glass without emerging into air.

(c) will emerge into air with an angle of refraction equal to $90^{\circ}$

(d)will neither be reflected not refracted but will be absorbed

Can you answer this question?

Refractive index of glass $=\sqrt 2$
$_a \mu _g =\sqrt 2$
$\therefore _g \mu _a =\large\frac{1}{\sqrt 2}$
angle of incidence from glass to air is $45^{\circ}$
$\therefore \large\frac{1}{\sqrt 2}=\frac{\sin 45}{\sin r}$
$\therefore \large\frac{1}{\sqrt 2}=\frac{1}{\sqrt \sin r}$
$\sin r=1$
$r=90^{\circ}$
Hence c is the correct answer.
answered Jan 16, 2014 by