Question

A plane wavefront is an incident on a water surface at an angle of incidence 60° then it gets refracted at 45°. The ratio of the width of incident wavefront to that of refracted wavefront will be ______ 

`[sin  pi/4 = cos  pi/4 = 1/sqrt2, sin60^circ = sqrt3/2, cos60^circ = 1/2]`

Options

• `sqrt3/2`

• `1/sqrt2`

• `sqrt2`

• `2sqrt3`

Answer 1

A plane wavefront is an incident on a water surface at an angle of incidence 60° then it gets refracted at 45°. The ratio of the width of incident wavefront to that of refracted wavefront will be `underline(1/sqrt2)`.

Explanation:

`W_1/W_2 = cosi/cosr = cos60^circ/cos45^circ  = (1/2)/(1/sqrt2) = sqrt2/2 = 1/sqrt2`