CHAPTER 9. DOPPLEREFFECT 9.2
Figure 9.1: Stationary sound sourceaway from the source atthe same rate in all directions. The distance between the peaks
represents the wavelength of the sound. The closer together the peaks, the higher the
frequency (or pitch) of the sound.
1
2
− 1
− 2
2 − 1 − 1 2
As this peak moves away, the source also movesand then emits the second peak. Now
the two circles are not concentric any more, but on the one side they are closer together
and on the other side they are further apart. This is shown in the next diagram.
1
2
− 1
− 2
2 − 1 − 1 2
If the source continuesmoving at the same speed in the same direction(i.e. with the
same velocity which youwill learn more about later), then the distance between peaks