A wave equation is represented as
`r = A sin [ alpha (( x - y)/(2)) ] cos [ omega t - alpha (( x + y)/(2))]`
where ` x` and `y` are in metres and t in seconds . Then ,

Options

A. The wave is a stationary wave
B. The waveis a progressive wave propagating along + x axis
C. The wave is a progressive wave propagating at right angle to the+ x axis
D. All points lying on line `y = x + (4pi)/(alpha)` are always at rest

Answer

D

Explanation

From the given equation we can see that option (D) is correct.