A wave travelling along positive x -axis is given by `y = A sin (omega t- kx)`. If it is reflected from rigid boundary such that 80% amplitude is reflected, then equation of reflected wave is

Options

A. `y=A sin (omega t-kx)`
B. `y=-0.8 A sin (omega t+kx)`
C. `y=0.8 A sin (omega t+kx)`
D. `y=A sin (omega t+0.8 kx)`

Answer

B

Explanation

On getting reflected form a rigid boundary the wave sufferes an additional phase change of `pi`.
`implies y-0.8 A sin (omega t+kx+pi)`
`=-0.8 A sin (omega t+kx)`