Question

When a sound wave is reflected from a rigid support then its path changes by

• A. $\lambda /2$
• B. $\lambda$
• C. $\pi$
• D. $2\pi$

Answer 1

The correct option is A $\lambda /2$

$\Delta y=\frac{\lambda }{2\pi }\Delta \varphi$,

Here $\Delta y$ is the path difference, and $\Delta \varphi$ is the phase differnce.

When sound wave reflects from a rigid boundary there is $\pi$ phase shift in the reflected wave. therefore from above relation,

$\Delta y=\frac{\lambda }{2\pi }\Delta \varphi =\frac{\lambda }{2\pi }\pi =\frac{\lambda }{2}$.

Option "A" is correct.