Question

A thin prism having refracting angle ${10}^o$ is made of glass of refractive index $1.42$. This prism is combined with another thin prism of glass of refractive index $1.7$. This combination produces dispersion without deviation. The refracting angle of second prism should be :

• A. ${10}^o$
• B. $4^o$
• C. $6^o$
• D. $8^o$

Answer 1

The correct option is C $6^o$

Prism, $r_1=10$, $n_1=1.42,n_2=1.7$

For Dispersion without deviation,

$A_2(H_2-1)=A_1(H_1-1)$

$r_2\left(0.7\right)=10\left(0.42\right)$

$r_2=6^0$