Sign Convention for Spherical Mirrors
The set of guidelines to set signs for image distance, object distance, focal length, etc for mathematical calculation during an image formation is called the Sign Convention. The sign conventions in the case of the spherical mirrors are made in taking into consideration that the objects are always placed on the left side of the mirror, such that the direction of incident light is from left to right.
The sign conventions followed for any spherical mirror are given as:
- All distances are measured from the pole of a spherical error.
- Distances measured in the direction of incident light are taken as positive, while distances measured in a direction opposite to the direction of the incident light are taken as negative.
- The upward distances perpendicular to the principal axis are taken as positive, while the downward distances perpendicular to the principal axis is taken as negative.
- For convenience, the object is assumed to be placed on the left side of a mirror. Hence, the distance of an object from the pole of a spherical mirror is taken as negative.
- Since the incident light always goes from left to right, all the distances measured from the pole (P) of the mirror to the right side will be considered positive (because they will be in the same directions as the incident light). On the other hand, all the distances measured from pole (P) of the mirror to the left will be negative (because they are measured against the direction of incident light)
Sign Convention for Spherical Mirrors
Sign Convention for Spherical Mirrors: While studying the reflection of light by spherical mirrors and the formation of images by spherical mirrors, a set of sign conventions are needed to learn that is required to measure the focal length, the distance of the object or image from the mirror, and the magnification of the mirror.
Before, understanding the concept of sign conventions for spherical mirrors first discuss some commonly used terms in a spherical mirror.
Table of Content
- Commonly Used Terms in Spherical Mirrors
- Sign Convention for Spherical Mirrors
- Important Points to Remember
- Mirror Formula
- Magnification (or Linear magnification)
- Solved Examples on Sign Conventions for Spherical Mirrors