The refractive indices of a prism for red, violet and yellow lights are `1.52, 1.62 and 1.59` recp.What is the dispersive power of the prism ? If mean deviation is `40^(@)`. What is angular dispersion produced by the prism ?

Answer

`0.169`; `6.76^(@)`

Explanation

Here, `mu_(r ) = 1.52, mu_(v) = 162` and `mu_(y) = 1.59`
Dispersive power `(omega)`
`= (mu_(v) - mu_(r ))/(mu_(y) - 1) = (1.62 - 1.52)/(1.59 - 1) = (0.10)/(0.59) = 0.169`
Angular dispersion : `delta_(v) - delta_(r ) = omega xx delta`
`= 0.169 xx 40^(@) = 6.76^(@)`