Frequency (GCSE Physics)
Frequency
Frequency
The frequency can be measured by looking at how many complete waves go past a certain point in one second. It is measured in Hertz, Hz.
The higher the frequency, the higher the pitch.
The Doppler Effect
As a stationary object emits waves, the wavefronts spread out at an equal distance.
However, when an object begins to move, the wave source also moves. This causes the waves to either become more squashed together or more stretched out.
If we imagine that a car begins to accelerate forward, the wavelength of the waves in front of the source will decrease and the frequency will increase. This is because the wavefronts are compressed as the car moves forward.
Behind the car, the opposite will occur as the wavefronts become more spread out. This change in frequency and wavelength as an object moves, relative to an observer, is called the Doppler effect.
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