A sinusoidal harmonic wave is propagating along a string stretched along x – axis. A particle on the string at x = 1 m is found to be at its mean position travelling in positive y direction at `t = 1 s`. The amplitude, wavelength and frequency of the wave are `0.01 m, pi/2m` and `20 Hz` respectively. Write the equation of the wave if-
(a) it is travelling along negative X direction
(b) it is travelling along positive X direction.

Answer

(a) `y=0.01 sin [40 pi (t-1)+4(x-1)]`
(b) `y=0.01 sin [40 pi (t-1)-4(x-1)]`