Draw a figure explaning various terms related to a lens.

1.	Draw a figure explaning various terms related to a lens.
Answer» Solution :1. Principal axis : The imagenary line passing through both centre of curvature is called the principal axis of the lens. 2. OPTICAL centre (O) : The point inside a lens on the principal axis, through which light rays pass wihtout changing their path is called the optical centre of a lens. 3. Principal focus fo convex lens: When the light rays paralled 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 fo convex lens. 4.Principal focus fo CONCAVE lens : Rays travelling paralled to the principal axis of a concave lens, diverge after passing through the lens and appear to be coming out from a point on principal axis. This point is called principal focus of concave lens. 5. Focal length (f) : The distance between the optical centre and principal focus of a lens is called its focal length. (`f_(1) and f_(2)`) Centre of curvature (C): The centre6. s of spheres whose parts form SURFACES of the LENSES are called centres of curvatures of the lenses. `(C_(1) adn (C_(2))` 7. Radius of curvature (r) : The radii of the spheres whose part form surfaces of the lenses are called the radii of curvature of the lens. `(R_(1) and (R_(2))`

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