Question

Light emerges out of a convex lens when a source of light is kept at its focus. The shape of the wavefront of the light is:

• A. Both spherical and cylindrical
• B. Cylindrical
• C. Spherical
• D. Plane

Hint:

A plane wavefront is produced when a convex lens converts spherical wavefronts into parallel rays by positioning the light source at its focal point.

Answer 1

The Correct Option is D

A wavefront is defined as the locus of points that oscillate in phase. When a point source of light is placed at the focal point of a convex lens, the rays of light emerging from the lens become parallel to each other. These parallel rays form a plane wavefront, as all points on the wavefront lie at the same distance from the source and propagate in the same direction. The convex lens transforms the initially spherical wavefront into a plane wavefront due to its focusing properties. Final Answer: \[ \boxed{\text{Plane}} \]