Draw a curve showing density or pressure variations with respect to distance for a disturbance produced by sound. Mark the position of compression and rarefaction on this curve. Also define wavelengths and time-period using this curve.

Wavelength is the distance between two consecutive compressions or two consecutive rarefaction of a wave sound. Wave length is represented by Greek letter λ (lambda). The SI unit of wavelength is metre (m).

Time period is the time taken to travel the distance between any two consecutive compression or rarefaction from a fixed point. The time period of sound wave is represented by letter ‘T’. The SI unit of time period is second (s).