Question

from a line source, if amplitude of a wave at a a distance r is A, then the amplitude at a distance 4r will be

• A. 2A
• B. A
• C. A/2
• D. A/4

Answer 1

The correct option is D A/4

$\begin{array}{c}I\left(intensity\right)\times \frac{1}{r^2}\\ I\times A^2\\ \therefore ,A\times \frac{1}{r}\\ ifr\to 4r,A\to \frac{A}{4}\end{array}$