Question

Which of the following is correct for light diverging from a point source ?

• A. The intensity decreases in proportion for the distance squared.
• B. The wavefront is parabolic.
• C. The intensity at the wavelength does not depend on the distance.
• D. None of these.

Answer 1

Answer: (A)

The intensity decreases in proportion for the distance squared.

A point source produces a spherical wavefront that moves in all the directions from the point.

Whereas the intensity at the wavelength is dependent on the distance and it follows the inverse square law. So, the intensity decreases with an increase in the distance from the source.

Thus, option $\left(A\right)$ is correct.