A Doppler shift is a phenomenon of a change in frequency based on the observer’s point of view. The most common analogy of this is standing on the side of the road and listen to a passing car. As the car approaches, there is a definitive sound. As the car passes, the sound changes to a lower frequency. This is called a Doppler Shift. There are two types of Doppler shifts:
- Red-Shift or a shift of frequency to a lower wavelength (away from the observer)
- Blue-Shift or a shift of frequency to a higher wavelength (toward the observer)
This is the equation for Doppler shift
= wavelength shift
= wavelength of the source not moving
v = velocity of the source
c = Speed of light
Apparent Frequency formula is given by
f= actual frequency of the sound wave
f ‘ = observed frequency
v =speed of sound waves
= velocity of observer
= velocity of the source