Question

A stone thrown into still water creates a circular wave pattern moving radially outwards. If r is the distance measured from the centre to the pattern, the amplitude of the wave varies as __________

(a) r^(-1/2)

(b) r^(-1)

(c) r^(-3/2)

(d) r^(-2)

This question was posed to me in an interview.

This question is from Beats topic in division Waves of Engineering Physics I

Answer 1

Right option is (a) r^(-1/2)

Explanation: For a circular wave,

I∝1/r

But A∝√I

A∝1/√r

A∝r^(-1/2).