Question

For a wave displacement amplitude is ${10}^{-8}m$, density for air $1.3kg.m^{-3}$, velocity in air $340m^{-1}$ and frequency is $2000Hz$. The average intensity of wave is

• A. $5.3\times {10}^{-4}W{m}^{-2}$
• B. $5.3\times {10}^{-5}W{m}^{-2}$
• C. $5.3\times {10}^{-8}W{m}^{-2}$
• D. $5.3\times {10}^{-6}W{m}^{-2}$

Answer 1

The correct option is C $5.3\times {10}^{-8}W{m}^{-2}$

$I=2{\pi }^2{f}^2{A}^{2}SVW$

$=2\times 3.14\times 3.14\times {\left(2000\right)}^2\times \left({10}^{-16}\right)\times 1.3\times 340$

$=2\times 9.86\times 4\times {10}^6\times {10}^{-16}\times 1.3\times 340$

$=5.3\times {10}^{-8}W{m}^{-2}$