Sign is taken as −( negative) from pole of a spherical mirror towards object along the principle axis. This sign convention is known as New cartesian sign convention. This sign convention is known as New Cartesian Sign Convention. In this convention, the pole (P) of the mirror is taken as the origin. This means sign is always taken as – (negative) in front of a spherical mirror. concave and convex mirrors. Sign convention for reflection of light through spherical lenses. All the distances parallel to the principal axis are always measured from the pole of the spherical mirror. Sign convention used in spherical mirrors The following sign convention is used for measuring various distances in the ray diagrams of spherical mirrors: Object is always placed to the left of mirror All distances are measured from the pole of the mirror. This means sign is always taken as −( negative) in front of a spherical mirror. The distance measured opposite … For example; the distance of object is always taken as – (negative) in case of both types of spherical mirror, i.e. The object is always placed to the left of the mirror. 3. Sign Convention for Spherical Mirrors (Concave and Convex Mirrors) Distances are to be measured from the pole (vertex) of the mirror marked by point V in the figure. The conventions are as follows - The principal axis of the mirror is taken as the x-axis (X'X) of the coordinate system. Sign convention is a set of rules to set signs for image distance, object distance, focal length, etc for mathematical analysis of image formation. Those distances measured opposite to the direction of incidence light … In numericals, we need to calculate some things likeObject distanceImage distanceObject heightImage heightFocal lengthTo calculate them correctly, we need to find whether it is positive or negativeThe sign convention mentioned below helps us in itWe can see the sign convention in … (iii) The distances measured against the direction of incident light are taken as negative. Answer. In a spherical mirror: ... Derivation of lens formula or mirror equation; Sign Conventions. In this convention, the pole (P) of the mirror is takenat the origin of X -Y coordinate system. Sign is taken as −(negative) from pole of a spherical mirror towards object along the principle axis. All the distances measured along the direction of incident light (along +ve x-axis), are considered to be positive. This means sign is always taken as −(negative) in front of a spherical mirror. According to it: Object is always placed to the left of mirror. The new Cartesian sign convention is used for measuring the various distances in the ray-diagrams of spherical mirrors. Sign Convention for Reflection by Spherical Mirrors . The principal axis of the mirror is taken as the x-axis (X'X) of the coordinate system. 2. According to the new Cartesian sign convention (figure 1) :     (i) The pole ‘P’of the mirror is taken as the origin and the principal axis of the mirror is taken as the x-axis of the coordinate system. For the measurement of all the distances, the optical center of the lens is considered. The conventions are as follows – (i) The object is always placed to the left of the mirror. We will use the New Cartesian Sign Convention for the reflection of light by spherical mirrors. In this convention, the pole (P) of the mirror is taken as the origin. New Cartesian Sign Convention for spherical lenses: (i) All the distances are measured from the optical centre of the lens. Sign is taken as – (negative) from pole of a spherical mirror towards object along the principal axis. Distances measured along the direction of the incident ray are positive. Refer to the diagram for clear visualization. (ii) The distances measured in the same direction as that of incident light are taken as positive. Sign conventions for reflection of light by spherical mirror are: 1. New Cartesian Sign Convention for spherical lenses: (i) All the distances are measured from the optical centre of the lens. Sign convention for reflection by spherical mirrors Reflection of light by spherical mirrors follow a set of sign conventions called the New Cartesian Sign Convention. All distances are measured from the pole of the mirror. 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