Question

A source of wave produces 40 crests and 40 troughs in 0.4 sec. Find the frequency of the wave.

Answer 1

As one crest and one trough together make a wave.

40 crests and 40 troughs are equal to 40 waves.

The source produces 40 waves in 0.4 seconds.

So, $Frequency=\frac{40}{0.4}=100Hz$.