A thin prism $\mathrm{P}_1$ with angle $4^{\circ}$ made of glass having refractive index 1.54 , is combined…
A thin prism $\mathrm{P}_1$ with angle $4^{\circ}$ made of glass having refractive index 1.54 , is combined with another thin prism $\mathrm{P}_2$ made of glass having refractive index 1.72 to get dispersion without deviation. The angle of the prism $P_2$ in degrees is
3
16/3
4
1.5
Solution
For dispersion without deviation, $\begin{aligned} & \left(\mu_1-1\right) A_1=\left(\mu_2-1\right) A_2 \\
& \Rightarrow \quad(1.54-1) 4^{\circ}=(1.72-1) A_2 \\
& \text { Or } A_2=\frac{0.54}{0.72} \times 4=3^{\circ} \end{aligned}$