Question

A thin prism $P_{1}$ with angle $4^{o}$ and made from glass $\left(\mu = 1 . 54\right)$ is combined with another prism $P_{2}$ made of another glass of $\mu =1.72$ to produce dispersion without deviation. The angle of prism $P_{2}$ is

• A. $53.3^{o}$
• B. $4^{o}$
• C. $3^{o}$
• D. $2.6^{o}$

Answer 1

Answer: (C)

For no deviation, $\left(\mu_{1}-1\right) A_{1}=\left(\mu_{2}-1\right) A_{2}$
$4^{o}\left(1 . 54 - 1\right)=\left(1 . 72 - 1\right)A_{2}$
$A_{2}=\frac{4 \times 0 . 54}{0 . 72}=3^{o}$ .