Question

The sound intensity is 0.008 W/m² at a distance of 10 m from an isotropic point source of sound. The power of the source is

• A. 2.5 watt
• B. 0.8 watt
• C. 8 watt
• D. 10 watt

Answer 1

Answer: (D)

10 watt

Answer 2

$\frac{P}{4\pi r^{2}}$ = I for an isotropic point sound source.

P = I.4pr²

= (0.008w/m²)(4.π.10²)

= 10 watt.