Question

A spherical source of power 87 W and
frequency 500 Hz is emitting sound waves.
What is the intensity of the waves at a distance
of 100 m?d
A) 8 W/m2 B) 2 x 104 W/m2
C) 10-5 W/m² D) 2 x 10-6 W/m2​

Answer 1

Given :

1) Power of spherical source = 87 W

2) Frequency of sound wave = 500 Hz

Distance, d = 100 m

To find :

Intensity of the waves at a distance of 100 m

Solution :

We know that,

• Intensity = Power / Area

where area = 4π×d^2 = 4π×(100)^2 m^2

Intensity, I = 87 / 4π×(100)^2

I = 87 / 4×3.14×10^4

I = 6.926×10^-4 W/m^2