Question

If we want to increase the intensity of a sound wave by 9 times, then

• A. Pressure amplitude must increase to 3 times
• B. Displacement amplitude must increase to 3 times
• C. Frequency amplitude must increase to 3 times
• D. Displacement amplitude must increase by 3 times and frequency must increase by 2 times

Answer 1

The correct option is A Pressure amplitude must increase to 3 times

Intensity $I=\frac{{P_{max}}^2}{2\rho \nu }$
where $P_{max}$ is the pressure variation or pressure amplitude (half the difference between the maximum and minimum pressure in the sound wave), $\rho$ is density of the material in which the sound wave travels and $v$ is the velocity of sound wave.

$\therefore I\propto {P_{max}}^2$