24Sound Doppler EffectHard1 mark
The diagram shows compressions and rarefactions in air as a sound wave moves from left to right.
A quieter sound of the same frequency is made.
What happens to the number of particles in a region of rarefaction and in a region of compression?
| number of particles in region of rarefaction | number of particles in region of compression | |
|---|---|---|
| A | decreases | decreases |
| B | decreases | increases |
| C | increases | decreases |
| D | increases | increases |