The defect in image formation for the wandering of the focus on the principal axis of a lens is called ______.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. spherical aberration.
Spherical aberration is an optical defect in lenses and mirrors with spherical surfaces. It occurs because light rays hitting the lens or mirror closer to its edges are refracted (bent) or reflected more strongly than those hitting closer to the center. This causes different rays from a single point source to focus at different points along the optical axis, instead of converging to a sharp, single focal point. The result is a blurred, less clear image, especially at wider apertures.