Question

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

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

Answer 1

The correct option is C 100 Hz

There are $20$ crests and $20$ trough in $0.2s$, which implies $20$ waves.

And if there are $20$ crests and $20$ trough, this mean that there are $20$ waves in $0.2s$

$\therefore$ Frequency$=$ Number of waves/ Time taken

$=\frac{20}{0.2}=\frac{200}{2}=100H_z$

$\therefore \nu =100H_z$

Option (C) is the correct answer.