A prism of a certain angle deviates the red and blue rays by `8^@` and `12^@` respectively. Another prism of the same angle deviates the red and blue rays by `10^@` and `14^@` respectively. The prisms are small angled and made of different materials. The dispersive powers of the materials of the prisms are in the ratio

Options

A. `5:6`
B. `9:11`
C. `6:5`
D. `11:9`

Answer

C

Explanation

Prism (1),
`omega_1=(delta_B-delta_R)/(delta)=(12-8)/(10)` (Since `delta=(delta_B+delta_R)/(2)`)
`=4//10=2//5`
Prism (2),
`omega_2=(delta_B-delta_R)/(delta)=(14-10)/(12)=1/3`
`omega_1//omega_2=(2//5)/(1//3)=6/5`