Question

When stationary wave is produced certain particles of the medium always remain at their positions and certain other positions particles vibrate simple harmonically about the mean positions with double the amplitude of each wave.

Answer 1

Dear Student,
Because at zero amplitude ( certain particle remain at their positions ) wave interferes destructively .
Hence cancel to each other .While at double amplitude ( certain particle has double distance from its
mean positions ) wave interferes constructively .So amplitude becomes double of initial .
Regards