Question

As a wave propagates

(i)The wave intensity remains constant for a plane wave.

(ii)The wave intensity changes inversely as the square of the distance from the source for a spherical wave.

(iii) The intensity of the spherical wave or at any spherical surface centered at source remains the same at all times.

The correct statement(s) is/are

• A. i and ii only
• B. i,ii and iii
• C. ii and iii only
• D. ii only

Answer 1

The correct option is A

i and ii only

The Amplitude of a plane wave remains constant and hence the intensity will be the same
For spherical wave: $I$ $\propto$ $\frac{1}{r^2}$