Chapter 14, Problem 1MCQ

To determine

The region of the sound spectrum.

Answer to Problem 1MCQ

Option (b).

Explanation of Solution

The audible range of the sound is $20\text{Hz}$ to $20\text{kHz}$. The sound frequencies below $20\text{Hz}$ are infrasonic. The given frequency of the sound wave is $15\text{Hz}$.

Therefore, the region of the sound spectrum is infrasonic.

Conclusion:

Since the audible frequency range of sound wave is $20\text{Hz}$ to $20\text{kHz}$. The frequency of the given sound is $15\text{Hz}$ which is not in audible region. Thus, option (a) is incorrect.

The frequency range of the sound wave below $20\text{Hz}$ is infrasonic region. Thus, option (b) is correct.

The frequency range of the sound wave above $20\text{kHz}$ is ultrasonic region. Thus option (c) is incorrect.

The frequency range of the sound wave above $20\text{kHz}$ is ultrasonic region or supersonic region. Thus option (d) is incorrect.