The Doppler Effect is the phenomenon where the frequency of a wave changes when there is relative motion between the source of the wave and the observer.
The Doppler Effect is caused by the compression or stretching of waves due to the motion of the source or observer. When the source is moving towards the observer, the waves are compressed, resulting in a higher frequency. When the source is moving away from the observer, the waves are stretched, resulting in a lower frequency.
The Doppler Effect can be observed in everyday situations such as the change in pitch of a siren as an ambulance passes by, the redshift and blueshift in astronomy, and the change in frequency of sound waves from a moving car or train.
The Doppler Effect has many practical applications, including radar technology, which uses the frequency change of radio waves to determine the speed and direction of moving objects. It is also used in medical imaging, such as ultrasound, to detect the movement of blood flow in the body.
The Doppler Effect is not limited to sound waves, but also applies to electromagnetic waves such as light. The frequency shift of light due to the motion of a source or observer is known as the Doppler shift, and it is a crucial factor in understanding the expansion of the universe and the redshift of distant galaxies.