Question

A sound wave source produces $30$ crests and $30$ troughs in $0.3$ second. Find the frequency of the wave.

$[$Assume complete crest and trough formation$]$

• A. $30\text{Hz}$
• B. $100\text{Hz}$
• C. $10\text{Hz}$
• D. $3\text{Hz}$

Answer 1

The correct option is B $100\text{Hz}$

One complete oscillation has one crest and one trough.

So, for $30$ crests and $30$ troughs, there will be $30$ oscillations in $0.3$ second.

So, frequency, $f=\frac{30}{0.3}=100\text{Hz}$