3.30 describe an experiment using an oscilloscope to determine the frequency of a sound wave

How to Measure the Frequency of a Wave using an Oscilloscope

The horizontal axis is time. The time between each division on the scale can be adjusted to get a clear, readable trace.

1. Adjust the time division setting until the display shows at least 1 complete cycle.
2. Read off the period (how long it takes to complete one cycle) in divisions.
3. Times the number of divisions by the time 1 division stands for
4. Frequency = 1 / Period

e.g. if 1 division = 0.0002s

And the period of 1 wave is 20 divisions.

20 x 0.0002 = 0.004s

Frequency = 1 / 0.004 = 250Hz