A plane wave of sound travelling in air is incident upon a plane water surface. The angle of incidence is 30°. If the velocity of sound in water is `1400"m s"^(-1)`, and the velocity of sound in air is `330"m s"^(-1)`, there will be

Options

A. Reflection only
B. Refraction only
C. both reflection and refraction
D. neither reflection nor refraction

Answer

A

Explanation

In this case, sound tends to go from air (lower velocity, `v_a`) to water (higher velocity `v_w`)- For such a surface, critical angle C is given by
`sin C = ( v_a)/( v_w) = (330)/( 1400) therefore C = 14^(@)`
As angle of incidence `=30^(@) gt C`, therefore, sound wave undergoes total reflection only.