Q.
Sound waves of ν=600Hz fall normally on a perfectly reflecting wall. The shortest distance from the wall at which all particles will have a maximum amplitude of vibration will be (speed of sound= 300ms−1 )
The wall acts like a rigid boundary and reflects this wave and sends it back towards the open end. At the open an antinode is formed and a node is formed at the wall. The distance between antinode and node is 4λ
Therefore, if v be the frequency of note emitted then λ=vv ⟹λ=600300=21m
Maximum amplitude is obtained at a distance =4λ=21×41=81m