Doppler Effect

Monday, 11 June 2018

12:46 PM

( - period of emitted wave at the source)

 

Summary

Moving Source

Moving Observer

 

 

 

 

Stationary source, stationary observer

 

Source towards stationary observer

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Source away from stationary observer

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Stationary source, approaching observer

 

Stationary source, receding observer

 

 

 

 

Machine generated alternative text: Doppler effect... • Consider a stationary sound emitting source, and two stationary observers. The frequency of the emitted sound wave isf= v/X. Both observers hear f. Wavelength 1 Observer R Wavefronts Sound speed Observer G

 

Machine generated alternative text: Doppler effect>Moving source... • Suppose now the observers are stationary, and only the sound source moves to the right with speed vs. Source moving away from observer T = Period of emitted at the source A" = 1 + vsT BLACKBOARD A" New wavelength Observer R Source moving towards observer 1' = A-vsT New wavelength Sound speed Observer G

 

Machine generated alternative text: Doppler effect>Moving source... • Suppose now the observers are stationary, and only the sound source moves to the right with speed vs. Source moving away from observer " =A+vsT v v vs -7+7 f" Source moving towards observer T = Period of emitted at the source Apparent frequency detected by observer G V V Vs 7

 

Machine generated alternative text: Doppler effect>Moving source recap... • If a sound source travels at speed vs, the apparent frequency detected by a stationary observer is Sound speed V Vs Original frequency of source Minus sign if source moves towards observer. Plus sign if source moves away from observer.

 

Machine generated alternative text: Last lecture... Doppler Effect • When both the observer and the source are moving, the Doppler shifted frequency is: o f'=f s \l/_ • Don't forget to flip the signs if you switch the direction the source and/or the observer relative to this picture.

 

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