Question

A thin isosceles prism with angle $4^{\circ }$ and refractive index 5/4 is placed inside a transparent tube with liquid (refractive index = 1.5) as shown. The deviation of light due to prism will be :-

• A. ${0.8}^{\circ }$ upward
• B. ${0.8}^{\circ }$ downward
• C. ${0.67}^{\circ }$ upward
• D. ${0.67}^{\circ }$ downward

Answer 1

The correct option is C ${0.67}^{\circ }$ upward

We know, the minimum deviation $8=(\mu -1)A$

Putting values according to the question

$8=(\frac{5/4}{1.5}-1)4^o=(\frac{5}{4}\times \frac{2}{3}-1)4^o=(-{0.67}^o)$

$\Rightarrow {0.67}^o$ upward.