Doppler Effect
Contents
Key Stage 4
Meaning
The Doppler effect is the apparent change in frequency and wavelength of a wave when its source is moving relative to the observer.
About The Doppler Effect
- When the source and observer are moving away from one another the wavelength of the wave will appear to be stretched longer and the frequency will be lower.
- When the source and observer are moving towards one another the wavelength of the wave will appear squashed shorter and the frequency will be higher.
- The Doppler effect can be noticed when cars pass by at high speed. At the cars are moving towards the observer the sound will be higher pitched but the moment the car goes past the sound will suddenly be lower pitched.
- The Doppler effect can be seen in the visible light emitted by objects moving at extremely high speed. Light from objects moving away form the observer will appear to be longer wavelength and is referred to as Red Shiftted while light from objects moving towards the observer will appear to be shorter wavelength and is referred to as Blue Shiftted.
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| This image shows a red object moving to the left.
An observer on the left of the object would experience higher frequency and shorter wavelength waves An observer on the right of the object would experience lower frequency and longer wavelength waves. |