Equation of a plane progressive wave is given by `y=0.6 sin 2pi(t-(x)/(2)).` On reflection from a denser medium, its amplitude becomes `2//3` of the amplitude of the incident wave. The equation of the reflected wave is

Options

A. `y = 0.6 sin 2pi (t + (x)/(2))`
B. `y = - 0.4 sin 2pi (t + (x)/(2))`
C. `y = 0.4 sin 2pi (t + (x)/(2))`
D. `y = -0.4 sin 2pi (t - (x)/(2))`

Answer

B

Explanation

When a progressive wave reflects from a denser medium, a phase change of `180^(@)` takes place.
New amplitude `= 0.6 xx (2)/(3) = 0.4`
So displacement of reflected wave
`y = 0.4 sin 2pi (t + (x)/(2) + pi)`
`=- 0.4 sin 2pi (t + (x)/(2))`
The correct option is (b).