The type of wavefront that emerges from a distant light source is -
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Plane
A wavefront is the surface of constant phase. A point source sends out spherical wavefronts, and at a very large distance a small part of a sphere of huge radius is practically flat, so the wavefront reaching us is a plane wavefront.
Why the other options are incorrect
Option (1) Cylindrical — Incorrect. A cylindrical wavefront comes from a line (slit) source, not from a distant point source.
Option (3) Diverging spherical — Incorrect. This is the wavefront close to a point source, before the radius has become very large.
Option (4) Converging spherical — Incorrect. This is the wavefront heading towards a focus, for example after a convex lens.
NCERT (2026-27):
Huygens Principle – “… If we have a point source emitting waves uniformly in all directions, then the locus of points which have the same amplitude and vibrate in the same phase are spheres and we have what is known as a spherical wave as shown in Fig. 10.1(a). At a large distance from the source, a small portion of the sphere can be considered as a plane and we have what is known as a plane wave [Fig. 10.1(b)].”
