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

Dispersive powe `(omega_(1)) = (delta_(B) - delta_(R ))/(delta_(Y)) = (12 -8)/( (12 + 8)/(2) ) `
`rArr " " omega_(1) = (4)/(10)`
`omega_(2) = (delta_(B) - delta_(R ))/( (delta_(B) + delta_(R ))/(2) ) = (14- 10)/((14 + 10)/(2) ) = (4)/(12) = (1)/(3)`
`therefore " " (omega_(1))/(omega_(2)) = (4 xx 3)/(10) = 1.2 = (6)/(5)` .