Derivation: Local action: ➡Zinc plate contains carbon an... 1. After getting refracted at point A again the ray Question: A bird is flying down vertically towards the surface of water in a pond with constant speed. Divide both sides by n1 we get, (1/v – 1/u) = (n2 – n1)/n1 (1/R1 – 1/R2) we get, n1 / v – n2 / v1 = n1 – n2 / R2 -------------------Eqn (2) 3. 4. we get, n2 / v1 – n1 / u = n2 – n1 / R1 -------------------Eqn (1) Tags: Class 10 , Physics , Light Reflection Refraction Asked by Rah Place a thin lens (which is made of one convex surface and one concave surface) between two refractive indices. Consider an object O placed on the principal axis Assumptions made to derive Lens maker formula : (i) The lens is thin and all the distances are measured from the optical centre of the lens. The lens is thin so that the distance measured from the poles of the two surfaces of the lens can be taken to be equal to the distances measured from the optical centre. 1/f = (1/v – 1/u) = (n – 1) (1/R1 – 1/R2) refractive index of medium is less than refractive index of lens), 2. the concave surface. convex surface. (ii) The aperture of the lens is small. 5. For refraction at surface XP1Y : O is the object and I1 is its real image. Lens makers formula: The lens maker's formula indicates that a convex lens can behave like a diverging one if m1 > m2 i.e., if the lens is placed in a medium whose m is greater than the m of lens. 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. For refraction at surface XP2Y : I1 is the virtual object and I is its real image which is the final image. Now consider a ray from object O incident on the Answered on: 2017/12/15 by ExamFear Education The convex lens act as converging lens (if We hope this clarifies your doubt. (iii) The object is a point object and lies on the principal axis. (iv) The angle made by incident ray and refracted ray with the principal axis are small. Using the formula, n2 / v – n1 / u = n2 – n1 / R1, we get, n2 / v1 – n1 / u = n2 – n1 / R1 -------------------Eqn (1). Polarization 1. If that fish is exactly vertically below the bird, then the bird will appear to the fish to be. Similarly a concave lens can be made convergent. R1 and R2 are the radii of curvature of surfaces XP1Y and XP2Y respectively. c) The aperture of the lens is small. at Q then we take, Object distance PO = -u, image distance PQ = v = x, The lens maker’s equation is another formula used for lenses that give us a relationship between the focal length, refractive index, and radii of curvature of the two spheres used in lenses. Adding equations (1) and (2), we get n1 (1/v – 1/u) = (n2 – n1)(1/R1 – 1/R2) radius of curvature R = R. 7. d) The incident as well as refracted ray makes small angle with the principal axis. 1. The convex lens acts as diverging lens (if 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. Derivation for lens makers formula . For refraction at surface XP1Y : O is the object and I1 is its real image. The image Q of object O due to the convex surface is taken as the object for This is the lens maker formula derivation. There is a fish inside the water. Also, n = n2 / n1 be the refractive index of the material of the lens with respect to the medium surrounding it. b) The object is a point object which is situated on the principal axis. Place a thin lens (which is made of one convex The lens maker’s equation for thin lenses is as given below as; 1/f = (n−1) (1/R1 − 1/R2) There is a fish inside the water. Derivation for lens makers formula 1/f = (n - 1) (1/R1 – 1/R2) is the equation of Lens Maker’s Formula. A platform to get information of physics and chemistry... A bird is flying down vertically towards the surface of water in a pond with constant speed. Assumptions: Let n a ... 1. R1 and R2 are the radii of curvature of surfaces XP1Y and XP2Y respectively. It is so called because it is used by lens manufacturers to make lenses of particular power from the glass of given refractive index. Consider a thin convex lens made of a material of absolute refractive index n2 , placed in a rarer medium of absolute refractive index n1. The Lens Maker’s Equation for Thin Lenses: \frac 1f ~= ~ (n-1) \left (\frac {1} {R_1}~-~ \frac {1} {R_2} \right) Using the formula for refraction at a single spherical surface we can say that, For the first surface, For the second surface, Now adding equation (1) and (2), When u = ∞ and v = f. But also, Therefore, we can say that, Where μ is the refractive index of the material. surface and one concave surface) between two refractive indices. According to image formation on curved surface Using the formula, n1 / v – n2 / u = n1 – n2 / R1, we get, n1 / v – n2 / v1 = n1 – n2 / R2 -------------------Eqn (2), Adding equations (1) and (2), we get n1 (1/v – 1/u) = (n2 – n1)(1/R1 – 1/R2), Divide both sides by n1 we get, (1/v – 1/u) = (n2 – n1)/n1 (1/R1 – 1/R2), 1/f = (1/v – 1/u) = (n2/n1 – 1) (1/R1 – 1/R2), 1/f = (1/v – 1/u) = (n – 1) (1/R1 – 1/R2), Answered on: 2017/12/15 by ExamFear Education. This is called lens maker s formula. The lens is thin so that the distance measured from the poles of the two surfaces of the lens can be taken to be equal to the distances measured from the optical centre. b) The object is a point object which is situated on the principal axis. formula. refractive index of medium is greater than refractive index of lens). axis at point I. : 1 Answers c) The aperture of the lens is small. Local action 2. There are two defects in voltaic cell. Answer this Question 8. get refracted due to concave surface at point B and reaches on the principal 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. It is so called because it is used by lens manufacturers to make lenses of particular power from the glass of given refractive index. of the thin lens. Using the formula, n1 / v – n2 / u = n1 – n2 / R1 Object distance PQ = u = x, Image distance = PI = v, (adsbygoogle = window.adsbygoogle || []).push({}); 1/f = (1/v – 1/u) = (n2/n1 – 1) (1/R1 – 1/R2) For refraction at surface XP2Y : I1 is the virtual object and I is its real image which is the final image. Tags: Class 10 , Physics , Light Reflection Refraction Asked by Rah 1 Answers. radius of curvature = -R, 1. Also, n = n2 / n1 be the refractive index of the material of the lens with respect to the medium surrounding it. 2. Consider a thin convex lens made of a material of absolute refractive index n2 , placed in a rarer medium of absolute refractive index n1. If there is no concave surface, it forms an image Answer, Tags: Class 10 , Physics , Light Reflection Refraction Asked by Rah. The complete derivation of lens maker formula is described below. 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