A large glass slab $\left( \mu = \frac{5}{3} \right)$ of thickness 8 cm is placed over a point source of light on a plane surface. It is seen that light emerges out of the top surface of the slab from a circular area of radius $R$ cm. What is the value of $R?$

Question

Dr. Abubacker · Accepted Answer

(a) $\frac{R}{t}	an	heta_{C}$
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Or $R = t\left( 	an	heta_{C} ight)$
But, $\sin	heta_{C} = \frac{1}{\mu} = \frac{3}{5}$
$	herefore	an	heta_{C} = \frac{3}{4}$
$R = \frac{3}{4}t = \frac{3}{4}(8\ cm) = 6\ cm$
Hence, the answer is 6.

Q. A large glass slab $\left( \mu = \frac{5}{3} \right)$ of thickness 8 cm is placed over a point source of light on a plane surface. It is seen that light emerges out of the top surface of the slab from a circular area of radius $R$ cm. What is the value of $R?$

Explanation

Reviewed by Dr. Abubacker

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