# Mini-Quiz: Doppler Effect Equations for Sound

by Ron Kurtus (revised 18 March 2012)

Take this Mini-Quiz to check your understanding of the lesson material.

1. If a source of sound was moving toward you at 1/3 the speed of sound, what would the resulting wavelength be?

It is impossible to find out

2/3 the emitted wavelength

3 times the emitted wavelength

2. If a horn blaring at 1000 Hz, but it is heard as 800 Hz, what is its velocity?

0.25 the speed of sound away from you

0.5 the speed of sound

0.75 the speed of sound toward from you

3. If you are standing next to the road, why does the pitch of the ambulance siren change as it comes toward you?

Its angle with respect you changes as it moves toward you, thus changing the relative velocity

The pitch is constant until the ambulance passes by

It is only an illusion that the pitch changes, due to changing air pressure

If you got all three correct, you are on your way to becoming a Champion in Physics. If you had problems, you had better look over the material again.

Be observant

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