Question

AC initially parallel cylindrical beam travels is a medium of refractive $\mu \left(I\right)={\mu }_0+N_{2}I$ where ${\mu }_0$ and ${\mu }_2$ as positive constants and I is intensity of the light beam. The intensity of the beam is decreasing with increasing radius. The initial shape of the wavefront of the beam is

• A. Convex
• B. Concave
• C. Convex neat the axis and Concave near periphery
• D. None of these

Answer 1

The correct option is D None of these

In the question it is given that it is a parallel cylindrical beam.

We know that cylindrical beam always form planar wavefronts. Hence the initial shape of the wavefront of the beam is planar.

Since none of the three options match the answer, option (D) is the correct answer.