Q.
The standing wave in a medium is expressed as y=0.2sin(0.8x)cos(3000t)m. The distance between any two consecutive points of minimum or maximum displacement is
y=0.2sin0.8xcos3000t
The distance between any two points of minimum or maximum displacement is simply wavelength (4λ) of the wave. k=λ2π=0.8
or λ=0.82π ∴λ=25πm ⇒4λ=85πm