The Doppler Effect

The Doppler Effect - The Doppler Effect The above analysis...

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The Doppler Effect The above analysis hinges on the fact that a traveler approaching a flashing light at 0.6 c will see it flashing at double its “natural” rate - the rate observed by someone standing still with the light - and a traveler receding at 0.6 c from a flashing light will see it to flash at only half its natural rate. This is a particular example of the Doppler Effect , first discussed in 1842 by the German physicist Christian Doppler. There is a Doppler Effect for sound waves too. Sound is generated by a vibrating object sending a succession of pressure pulses through the air. These pressure waves are analogous to the flashes of light. If you are approaching a sound source you will encounter the pressure waves more frequently than if you stand still. This means you will hear a higher frequency sound. If the distance between you and the source of sound is increasing, you will hear a lower frequency. This is why the note of a jet plane or a siren goes lower as it passes you. The details of the Doppler Effect for sound are a little different than those for light, because the speed of sound is not the same for all observers - it’s 330 meters per second relative to the air. It isn’t difficult to find the general formula for the Doppler shift, that is, the change in frequency
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The Doppler Effect - The Doppler Effect The above analysis...

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