Question

The refractive indices of material for red, violet and yellow colour light are 1.52, 1.62 and 1.59 respectively.
Calculate the dispersive power of the material. If the mean deviation is 40°. What will be the angular dispersion produced by a prism of this material?

Answer 1

We know `omega = ("n"_"V" - "n"_"R")/("n"_"Y" - 1)`

Given  `"n"_"V" = 1.62, "n"_"R" = 1.52` and `"n"_"Y" = 1.59`

So, `omega = (1.62 - 1.52)/(1.59 - 1)`

= 0.1695

Angular dispersion between red and violet rays is:

`theta = δ_"v" - δ_"R"`

`theta = omega xx δ_"Y"`

So, `theta = 0.169 xx 40^circ`

`theta = 6.78^circ`