What is Doppler effect ?

 The Doppler effect is the apparent change in the frequency or wavelength of a wave observed when there is relative motion between the wave source and the observer. It occurs for all types of waves, including sound, light, and water waves.

Explanation:

• When the wave source moves toward the observer, the waves get compressed, leading to a higher frequency and shorter wavelength (perceived as a higher pitch for sound).
• When the wave source moves away from the observer, the waves stretch out, resulting in a lower frequency and longer wavelength (perceived as a lower pitch for sound).

Example:

• Sound: The change in the pitch of an ambulance siren as it moves past you.
• Light: Astronomers observe the Doppler effect in starlight to determine whether stars and galaxies are moving closer or farther away from Earth.

Formula (Sound Waves):

For sound waves, the observed frequency $f'$ is given by:

$$f' = f \frac{v + v_o}{v - v_s}$$

Where:

• $f'$: Observed frequency
• $f$: Source frequency
• $v$: Speed of sound
• $v_o$: Speed of the observer (positive if moving toward the source)
• $v_s$: Speed of the source (positive if moving away from the observer)

The Doppler effect is widely used in various fields such as radar, medical imaging, and astrophysics.