Question

Write a short note on intensity.

Answer 1

The intensity of sound is defined as “the sound power transmitted per unit area taken normal to the propagation of the sound wave”. The intensity of sound is inversely proportional to the square of the distance from the source.

Intensity of sound waves

I = `"Power of the source"/(4pi"r"^2)`

`=> "I" prop 1/"r"^2`

This is known as the inverse square law of sound intensity. Two sounds with the same intensities need not have the same loudness. For example, the sound heard during the explosion of balloons in a silent closed room is very loud when compared to the same explosion happening in a noisy market.

If the intensity of sound is increased then loudness also increases. Loudness depends on both intensities of the sound wave and sensitivity of the ear.