Sign in the case of concave mirror: Since, object is always placed in front of the mirror hence object distance is taken as negative. what is the new cartesian sign conventions of concave and convex lens separately . A concave lens bulges inward and is thinner in the middle and thicker at the edges. Because a lens transmits light rather than reflecting it like a mirror does, the other side of the lens is the positive side for images. The sign convention comes from the sign convention of the u and f distances. According to it: Object is always placed to the left of lens. The sign convention for lenses is similar to that for mirrors. The distance from the vertex to the center of curvature is the radius of curvature of the surface. Since, the centre of curvature and focus lie in front of the concave mirror, so radius of curvature and focal length are taken as negative in the case of concave mirror. Asked by aniket | 29th Oct, 2013, 08:29: PM. Refer to the diagram for clear visualization. Again, take the side of the lens where the object is to be the positive side. Radius of curvature (ROC) has specific meaning and sign convention in optical design.A spherical lens or mirror surface has a center of curvature located either along or decentered from the system local optical axis.The vertex of the lens surface is located on the local optical axis. Hence the same focal length. A lens, whether it is a convex lens or a concave lens, has two spherical surfaces which form a part of a sphere. For the measurement of all the distances, the optical center of the lens is considered. The signs of the lens' radii of curvature indicate whether the corresponding surfaces are convex or concave. This plano concave lens has the same object and image positions as your silvered plano convex lens. All distances are measured from the optical centre of the mirror. Sign convention - definition Sign convention is a set of rules to set signs for image distance, object distance, focal length, etc for mathematical analysis of image formation. Such lenses diverge light rays as shown in Figure 1(b) Such lenses are called diverging lenses. For a Concave lens,There are only 2 casesThey areObject is Placed at InfinityObject is Placed between Infinity and Optical CenterCase 1 - Object is Placed at infinityIn this Case, Object is kept far away from mirror (almost at infinite distance)So, we draw rays parallel to principal axisSince ray pa Expert Answer: New Cartesian sign convention for refraction of light through spherical lenses (i.e. Derivation of lens formula or mirror equation; Sign Conventions. 14.4k 3 3 gold badges 26 26 silver badges 50 50 bronze badges $\endgroup$ … New Cartesian Sign Convention is used to avoid confusion in understanding the ray directions. share | cite | improve this answer | follow | answered Nov 21 '15 at 4:31. mmesser314 mmesser314. both convex and concave lens): According to this sign convention: (i) All distances are measured from the optical centre of the lens. Fig: Cartesian Sign Convention. The lens ' radii of curvature is the new Cartesian sign Conventions of concave and convex.! 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