A lens has two principal focus, usually named F1 and F2. Lens is an optical device which converges or diverges the rays of light before transmitting. Centre of curvature: The centre of sphere of part of which a lens is formed is called the centre of curvature of the lens. Centres of curvature : A lens has two spherical surfaces. Concave lens also have two focii, usually named F. Each of these surfaces forms a part of a sphere. The lens is a transparent medium bounded by two surfaces and at least one of them must be curved. Focus: Point at which parallel rays of light converge in a concave lens and parallel rays of light diverge from the point is called Focus or Principal Focus of the lens. The centre of curvature of a lens is usually represented by the letter C. Since there are two centres of curvature, we may represent them as C1 and C2. NCERT Lens Science Chapter Class 10 Note. This is called refraction. So we can conclude that a convex lens need not necessarily be a converging and a concave lens diverging. The centres of these spheres are called centres of curvature of the lens. Filed Under: Class 10, Light-Reflection and Refraction Tagged With: application of lens, diopter, power of lens About Mrs Shilpi Nagpal Author of this website, Mrs Shilpi Nagpal is MSc (Hons, Chemistry) and BSc (Hons, Chemistry) from Delhi University, B.Ed (I. P. University) and has many years of experience in teaching. When rays parallel to principal axis gets refracted by concave lens , they appear to diverge from a point on the principal axis , this point is called Principal focus. Convex lens is the most commonly used lens in our day to day life. Concave and Convex lens are most commonly use spherical lens. The central point of a lens is its optical centre. Concave lens: It is a lens which is thicker at the center and thicker at the edges. Learn this Physics module on Centre of curvature to score full marks in ICSE class 10 Board exams. Convex lens is the most commonly used lens in our day to day life. A lens has two spherical surfaces. Optical centre: The central point of a lens is called its Optical Centre. Convex lens converges the light rays as shown below in the figure 1(a). If you pass parallel rays from opposite side of lens you get another principal focus on the opposite side. It is also known as biconcave lens because of two spherical surface bulging inwards. Applications of Lenses Class : 10th Class Subject : Physics Chapter : Geometrical optics Topic : Applications of lenses Focal length of a lens is half of the radius of curvature. Register free for online tutoring session to clear your doubts. Answer: The ratio of sine of angle of incidence to the sine of angle of refraction remains constant subject to certain conditions. Oswaal CBSE Question Bank Class 10 Hindi B, English Communication Science, Social Science & Maths (Set of 5 Books) Combo Pack: Science for Class 10 () Lakhmir Singh; Together with CBSE/NCERT Practice Material Chapterwise for Class 10 Science; Mastering Numericals and Objectives of Physics for Class X A lens having two spherical surface bulging outwards is called Convex Lens. A lens will be converging with positive focal length, and diverging if the focal length is negative. types of lens Introduction to Lenses 10th class physics Chapter 12 Geometrical Optics online lecture The effective diameter of the circular outline of a spherical lens is called its aperture. A concave lens bulges inward and is thinner in the middle and thicker at the edges. Centre of curvature - Flash Card Notes It is also known as biconvex lens because of two spherical surface bulging outwards. A convex lens bulges outward and is thick at the center and thinner at the edges. 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