Question

If the amplitude of waves at a distance r from a point source is A, the amplitude at a distance 2r will be –

• A. 2A
• B. A
• C. A/2
• D. A/4

Answer 1

Answer: (C)

A/2

Answer 2

For point source

I µ $\frac{1}{r^{2}}$µ a² ....(1)

I¢ µ $\frac{1}{(2r)^{2}}$µ a¢ ² ....(2)

Divide a¢ = a/2