Doppler+Effect

**The Doppler Effectmedia type="youtube" key="iN3fO5l4Rww" width="350" height="300" align="right"**
The sudden change in pitch of a car horn as a car passes by or in the pitch of a boom box on the sidewalk as you drive by in your car was first explained in 1842 by Christian Doppler. The Doppler Effect is the change in frequency (or wavelength) produced when a moving source generates waves.

The Doppler effect relates to sound because it changes the way you hear moving objects and explains how it works through different wavelengths and frequencies.

The wavelength of the sound waves in front of the moving car are smaller than the sound waves behind the moving car.The smaller the wavelength, the higher the frequency so the horn in front the car appears to sound higher. The larger the wavelength, the lower the frequency, so the horn behind the car appears to sound lower. This is why when the car passes, you hear a lower sound.

Janelle

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