Question

A ray of light in the fashion as shown in fig. After thro 'Water the ray grazes along water air interface. The value of RI of glass in terms of i is-

• A. $\frac{1}{sini}$
• B. $\frac{3}{3sini}$
• C. $\frac{4}{3sini}$
• D. sin i

Answer 1

The correct option is A $\frac{1}{sini}$

$\begin{array}{c}\text{At point}A\\ \begin{array}{c}1\times \sin \theta -{\mu }_1\sin i-\left(i\right)\\ \text{at}B\text{,}\\ {\mu }_1\sin i=\frac{4}{3}\times \sin r-\left(ii\right)\end{array}\end{array}$

$\frac{4}{3}\sin r=1\times \sin {90}^{\circ }\dots \left(iii\right)$

$\text{from (i),(ii), (iii)}$

$\begin{array}{c}\sin r=\frac{3}{4}\Rightarrow r={37}^{\circ }\\ \sin i=\frac{1}{{\mu }_1}\Rightarrow {\mu }_1=\frac{1}{\sin i}\end{array}$