Question

The energy per unit area associated with a progressive sound wave will be doubled if:

• A. The amplitude of the wave is doubled
• B. The amplitude of the wave is increased by 50%
• C. The amplitude of the wave is increased by 41%
• D. The frequency of the wave is increased by 50%

Answer 1

The correct option is A The amplitude of the wave is doubled

Total Energy $=\frac{1}{2}m{\omega }^2{A}^2$

$Area\alpha A\left(\frac{\lambda }{2}\right)Area=\frac{KA\lambda }{2}constant$

Energy per unit area $=\frac{\frac{1}{2}m{\omega }^2{A}^2}{\frac{KA\lambda }{2}}$

$\Rightarrow$ Energy per unit area$\alpha A$

So, to double energy per unit area , A should be doubled.