Question

A thin glass prism ($\mu$ = 1.5) is immersed in water ($\mu$ = 1.3). if the angle of deviation in air for a particular ray be D, then that in water will be

• A. 0.2 D
• B. 0.3 D
• C. 0.5 D
• D. 0.6 D

Answer 1

Answer: (B)

0.3 D

$\begin{array}{c}\text{Deviation produced by a thin prism}\\ d=(n_{\gamma }-1)A{n}_{\gamma }\to \text{relative refractive index of prism}\\ \text{Given}{d}_{air}=DA\to \text{refracting angle}\end{array}$

$\begin{array}{c}{d}_{air}=(1.5-1)A\\ d_{water}=(\frac{1.5}{1.3}-1)A\\ \frac{d_{air}}{d_{water}}=\frac{0.5}{0.2}\times 1.3\\ \Rightarrow d_{water}=0.3d_{air}=0.3D\end{array}$