u = Distance of object from the optical center of the lens. 3)Aperture of lens should be small. 2. Lens makers formula: It is a relation between the focal length of a lens to the refractive index of its material and the radii of curvature of its two surfaces. Let us consider a thin lens made up of a medium of refractive index ? Let us consider the thin lens with 2 refracting surfaces having the radii of curvatures R1 and R2 respectively. 1.Let R 1 and R 2 be the radii of curvature of two spherical surfaces ACB and ADB respectively and P be the … f = focal length of the lens. Derivation for lens makers formula . Let the refractive indices of the surrounding medium and the lens material be n1 and n2 respectively. u = Distance of object from the optical center of the lens. Lens Formula Derivation. Here is a deriation for lens makers formula: Assumptions. Lens maker s formula and lens formula . Tags: Class 10 , Physics , Light Reflection Refraction Asked by Rah 1 Answers. Convex Lens Derivation Such rays are called paraxial rays. Lens Formula Derivation Convex Lens 2 placed in a medium of refractive index ? Applicable for both the convex and concave lenses, the lens formula is given as: 1/v - 1/u = 1/f Where, v = Distance of image formed from the optical center of the lens. The ray diagram is as follows: Note: The lens maker's formula indicates that a convex lens can behave like a diverging one if m 1 > m 2 i.e., if the lens is placed in a medium whose m is greater than the m of lens. f = focal length of the lens. We assume a thin, converging lens and that the light rays we are dealing with are close to the principal axis and make very small angles with the principal axis ( angles of less than 10 o), resulting in very small angles of incidence. Similarly a concave lens can be made convergent. 1. Derivation of Lensmaker’s formula. Basic assumptions used in deviation of lens maker formula are as follow: 1)The lens should be thin so that distances measured from its surface may be taken equal to those measured from optical centre . The lens maker's formula can be derived for a concave lens in the same way. 2)Object should be a point object. Applicable for both the convex and concave lenses, the lens formula is given as: 1/v - 1/u = 1/f Where, v = Distance of image formed from the optical center of the lens. ... Derivation.