When a ray is refracted from one medium into another, the wavelegths changes from `6000Å` to `4000Å`. The critical angle for a ray from the second medium will be

Options

A. `cos^(-1)(2/3)`
B. `sin^(-1)(2/sqrt3)`
C. `sin^(-1)(2/sqrt3)`
D. `cos^(-1)(2/sqrt3)`

Answer

C

Explanation

(c ) As `""_(1)mu_(2)=1/sinC`
`rArr mu_(2)/mu_(1)=lamda_(1)/lamda_(2)=1/sinC`
`rArr 6000/4000=1/sin C`
`rArr` Criticle angle, `C=sin^(-1)(2/3)`