Question

For a wave, displacement amplitude is ${10}^{-8}$ m, density of air is 1.3 Kg/$m^3$, velocity in air is 340 m/s and frequency is 2000 Hz. The intensity of the wave will be given by

• A. $5.3\times {10}^{-4}W/m^2$
• B. $5.3\times {10}^{-6}W/m^2$
• C. $3.5\times {10}^{-8}W/m^2$
• D. $3.5\times {10}^{-6}W/m^2$

Answer 1

The correct option is D $3.5\times {10}^{-6}W/m^2$

$I=2{\pi }^2\rho f^{2}v{A}^2$
$\Rightarrow I=2\times (3.14{)}^2\times (1.3)\times (2\times {10}^3{)}^2\left(340\right)({10}^{-8}{)}^2$
$\Rightarrow I=3.5\times {10}^{-6}w/m^2$