Question 113: Ray Optics

Question

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 $\mathrm{P}_2$ in degrees is

Accepted Answer

We know, for thin prism,
$$\mu  = {{A + \delta } \over A}$$
where, $\mu$ = refractive index
A = Angle of prism
$\delta$ = Angle of deviation
We can write, $$\mu A = A + \delta $$
$$ \Rightarrow \delta  = (\mu  - 1)A$$
given, $${\delta _{net}} = 0$$
$$ \Rightarrow ({\mu _1} - 1){A_1} - ({\mu _2} - 1){A_2} = 0$$
$$ \Rightarrow (1.54 - 1)4 - (1.72 - 1){A_2} = 0$$
$$ \Rightarrow {A_2} = {{54 	imes 4} \over {72}} \Rightarrow {A_2} = 3^\circ $$

Answer

1.5

Answer

16/3

Answer

3

Answer

4

Ray Optics

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 \mathrm{P}_2 in degrees is

Choose the correct answer: