General Formula of Lens The relation among object distance, image distance and focal length of a lens is known as general formula of lens . Convex lens and real image: in Fig., LL’ is a convex lens . An object FQ is placed perpendicular to the principal axis of the lens . What is lens formula ? Lens formula is the relation between the position of object, position of image and focal length of lens taking the optical center of lens as origin. The lens formula is used for both convex and concave lenses . The lens Formula is used for finding the image distance, determining the type of image formed and the focal length of the lens . The lens formula is applicable for both types of lenses , concave and convex lenses . lens Formula is 1/u + 1/v = 1/f Derivation of this is available here.
