Draw a figure explaining various terms related to a lens

1.	Draw a figure explaining various terms related to a lens
Answer» Solution : i. Principal axis: The imaginary line passin through both centres of curvature is called th! principal axis of the lens. ii. OPTICAL centre: The point INSIDE a lens on the principal axis, through which light RAYS PASS without changing their paths is called the optical centre of a lens. iii. Centre of curvature: The centre of sphere whose part forms the surface of the lens is called centre of curvature of the lens. iv. Radius of curvature: The radius of the sphere whose part forms the surface of the lens is called radius of curvature of the lens. v. Principal focus: a. When light rays parallel to the principal axis are INCIDENT on a convex lens, they converge to a point on the principal axis. This point is called the principal focus of the lens. b. Rays travelling parallel to the principal axis of a concave lens diverge after refraction in such a way that they appear to be coming out of a point on the principal axis. This point is called the principal focus of the concave lens. vi. Focal length: The distance between the optical centre and principal focus of a lens is called its focal length.

Discussion