Sound Wave Formulae for NEET

A sound is a vibration that propagates through a medium in the form of a mechanical wave. The medium in which it propagates can either be a solid, a liquid or a gas. Sound travels fastest in solids, relatively slower in liquids and slowest in gases.

Longitudinal displacement of the sound wave

y = A sin (ωt – kx)

  1. Speed of Sound

    C =

    Where E = Elastic modulus for the medium

    = density of the medium

  2. Loudness of sound

    L = 10 log10(I/I0) dB

    I0 = the minimum intensity human ear can hear

    I = intensity at a distance r from the point source

  3. Open organ pipe

    f = ,,……

  4. Closed organ pipe

    f = ,,……

  5. Beat frequency

    Beat frequency =

  6. Doppler Effect

    The observed frequency f’ = f (v-v0/v-vs)

    Apparent wavelength λ’ = λ ((v-vs/v)