Doppler effect for sound waves (7.3)

What is the doppler effect?

Doppler effect - the change in observed frequency when a source moves relative to the observer

How does the observed frequency change depending on whether the source is moving to or away from the observer?

Source moving towards

• The wavelengths shorten

• The frequency increases

Source moving away

• The wavelength increases

• The frequency decreases

How do you calculate the doppler shift?

Where f₀ is the observed frequency in Hz

Where f_s is the frequency emitted by the source in Hz

Where v is the speed of the wave in ms-1

Where v_s is the speed of the source

Use a + when the source is moving away as the frequency decreases

Use a - when the source is moving towards as the frequency increases

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