There are eight Doppler Effect Formulas
for frequency depending on cases:
(i) When the source is moving towards a observer at rest
(ii) When the source is moving away from the observer at rest
(iii) When observer is moving towards the stationary source
(iv) When observer moving away from a stationary source
(v) When both Source and observer moves towards each other
(vi) When both Source and observer move away from each other
(Vii) When the Source is approaching the Stationary observer and observer moving away from it
(Viii) When the Observer is approaching the Stationary source and source moving away from it
= Velocity of the Source,
= Velocity of the Observer,
v = Velocity of sound or light in medium,
f = Real frequency,
f' = Apparent frequency.
Doppler effect formula is used to find the apparent frequency and wavelength for the source moving towards the observer and away from the observer or observer moving towards the source or away from the source.