Question

The amplitude of a light wave becomes n times. This results in the intensity of the wave becoming m times. What is the relation between n and m?

Answer 1

The intensity I of a wave is proportional to the square of its amplitude, 4, i.e.,

I ∝ A²

If the amplitude becomes n times the original value, the intensity becomes m times then,

I' = kA²

mI = k(nA)²

mI = kn²A²

m = n²