GENERAL KNOWLEDGE

Detailed explanation-1: -Any surface that is curved has a radius of curvature, the radius of the sphere that approximates the surface locally. Thus a spherometer can measure the radius of curvature of an item such as a lens and curved mirrors that are spherical in shape.

Detailed explanation-2: -A spherometer is so-called because it is used for measuring the radii of curvature of spherical surfaces.

Detailed explanation-3: -The radius of curvature of a concave mirror measured by a spherometer is given by R=6hl2+2h. The measured value of l is 3cm using a meter scale with least count 0.