My teacher also said that it would be positive but I have read in many places on the internet that it is negative. The focal length is positive for 'real focal points'--meaning light *actually* converges at the focal point, and is negative for 'virtual focal points'--light only *appears* to converge at a focal point. An object is placed at a distance of 6 cm from a convex mirror of focal length 12 cm. Log in. According to the Cartesian sign convention, the focal length should be positive since the convex mirror forms a virtual image to the right of mirror (positive direction) when light comes from left. The image can be obtained on the screen as the image formed by the lens is real. Nos partenaires et nous-mêmes stockerons et/ou utiliserons des informations concernant votre appareil, par l’intermédiaire de cookies et de technologies similaires, afin d’afficher des annonces et des contenus personnalisés, de mesurer les audiences et les contenus, d’obtenir des informations sur les audiences et à des fins de développement de produit. Its height, being upward, is taken positive. Correct. a photographic lens or a telescope), the focal length is often called the effective focal length (EFL), to distinguish it from other commonly used parameters: . the distance from the center of the lens to that point is called the lens’s focal length. When the image distance is positive, the image is on the same side of the mirror as the object, and it is real and inverted. Convex mirror: Its inner concave surface is polished and outer convex surface reflects. Ask your question. If a concave mirror has a focal length of 10 cm, find the two positions where an object can be placed to give, in each case, asked Jun 23 in Physics by AmanKumar ( 51.7k points) reflection of light Click here to get an answer to your question ️ Which type of mirror has :; (a) positive focal length? Focal Length of Spherical Mirrors. If a concave mirror has a focal length of 10 cm, find the two positions where an object can be placed to give, in each case. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students. f is the focal length which is the difference between the optical centre of the lens and the principal focus. Découvrez comment nous utilisons vos informations dans notre Politique relative à la vie privée et notre Politique relative aux cookies. Pour autoriser Verizon Media et nos partenaires à traiter vos données personnelles, sélectionnez 'J'accepte' ou 'Gérer les paramètres' pour obtenir plus d’informations et pour gérer vos choix. 1. Find the position of the image. Join now. Draw a ray-diagram showing the formation of image. When you use the mirror equation--or the thin lens equation, the object distance is always positive. Log in. Their distances (radius of curvature and focal length) become negative. vishavjasrotia4253 vishavjasrotia4253 23.07.2019 Physics Secondary School Which type of mirror has : (a) positive focal length ? Solution: We have u = –15 cm and f = –10 cm Which type of mirror has negative focal length? The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror. Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Find the size and position. For a thick lens (one which has a non-negligible thickness), or an imaging system consisting of several lenses or mirrors (e.g. A plane mirror is placed at origin parallel to y-axis, facing the positive x-axis. If a concave mirror has a focal length of 10 cm find the two positions where an object can be placed to give in each case an image twice the height of the object. asked Aug 1, 2019 in Class X Science by aditya23 ( -2,145 points) For convex mirror, centre of curvature and focus lie behind to the right. An object is placed at a distance of 10 cm from a convex mirror of focal length 5 cm. Join now. (b) Types: There are two types of spherical mirrors: Concave mirror: Its outer convex surface is polished and inner concave surface reflects. At what distance from a concave mirror of focal length 10 cm should an object be placed so that. For concave mirror, centre of curvature and focus lie in front of it to the left of pole. Find the position and nature of the image. View Answer. (b) negative focal length ? Example 4: An object is placed at a distance of 15 cm from a concave mirror of focal length 10 cm. Real object stands erect. Vous pouvez modifier vos choix à tout moment dans vos paramètres de vie privée. Spherical mirror (a) Definition: A mirror whose surface is cut out of a spherical shell, is called a spherical mirror. The focal length, is positive for a concave mirror, and negative for a convex mirror. When the image distance is negative, the image is behind the mirror… Yahoo fait partie de Verizon Media. Solution: The radius of curvature of the mirror = 30 cm Thus, the focal length of the mirror =\(\frac { 30 cm }{ 2 } \) = 15 cm. An object 1 cm tall is placed 30 cm in front of a convex mirror of focal length 20 cm. 1. An ordinary convex lens focuses a parallel beam of light entering say on the left side of the lens to a focal point on the right side. If a concave mirror has a focal length of 10 cm, find the two positions where an object can be placed to give, in each case, asked Jun 23 in Physics by AmanKumar ( 51.7k points) reflection of light To determine focal length of a given concave mirror Materials Required. ; (b) negative focal length? Informations sur votre appareil et sur votre connexion Internet, y compris votre adresse IP, Navigation et recherche lors de l’utilisation des sites Web et applications Verizon Media. Their distances become positive.