A sound wave travelling with a velocity `V` in a medium `A` reaches a point on the interface of medium `A` and medium `B`. If the velocity in the medium `B` be `2 V`, then the angle
of incidence for total internal reflection of the wave will be greater than:

Options

A. `15^(@)`
B. `30^(@)`
C. `45^(@)`
D. `90^(@)`

Answer

B

Explanation

The medium having lower wave velocity is denser. `TIR` will take place, when wave move from denser to rarer medium. Incidence angle is equal to critical angle when angle of refraction is `90^(@)`

`(sin i)/(sin r) = (v_(A))/(v_(B)) rArr (sin C)/(sin 90^(@)) = (V)/(2 V)`
`C = 30^(@)`