Question

A wave source produces $20$ crests and $20$ troughs in $0.2seconds$. Find the frequency of the wave.

• A. $200Hz$
• B. $500Hz$
• C. $100Hz$
• D. $300Hz$

Answer 1

The correct option is C

$100Hz$

A crest is the maximum value of the wave quantity. A trough is a minimum value of the wave quantity. One crest and one trough combine to form one wave. The distance between consecutive crests or consecutive trough is called wavelength.

Frequency is the number of waves per unit time. The source is generating $20$ waves(i.e 20 crests and 20 troughs) per $0.2s$. So, per second source will generated $20/0.2$ waves. The frequency is $100Hz$