A spherical source of power 4 W and frequency 800 Hz is emitting … - Vidyadip

MCQ

A spherical source of power $4 W$ and frequency $800 Hz $ is emitting sound waves. The intensity of waves at a distance $200 m$ is

✓
$8 \times {10^{ - 6}}\,W/{m^2}$
B
$2 \times {10^{ - 4}}\,W/{m^2}$
C
$1 \times {10^{ - 4}}\,W/{m^2}$
D
$4\,W/{m^2}$

✓

Answer

Correct option: A.

$8 \times {10^{ - 6}}\,W/{m^2}$

a
(a) Intensity = $\frac{{{\rm{Power}}}}{{{\rm{Area}}}} = \frac{4}{{4\pi \times {{(200)}^2}}} = 7.9 \times {10^{ - 6}}$$W/{m^2}$

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