A piezoelectric crystal in a monitoring device sends a sound wave through a layer of oil and into a steel plate.
The wave reaches the oil–steel boundary at a small angle to the normal.
The crystal completes 20 oscillations in 8.0 μs8.0\ \mu\text{s}8.0 μs.
| Medium | Speed of sound in m/s\text{m/s}m/s |
|---|---|
| oil | 1400 |
| steel | 5900 |
Calculate the separation between adjacent compressions of the sound wave while it is travelling through the oil.
Calculate the percentage increase in the wavelength when the sound wave enters the steel.
Explain the changes to the sound wave as it enters the steel. Your answer should refer to its wavelength, its direction and whether it can be heard by a person with normal hearing.