Sign Convention for Spherical Mirrors
1 . All distances are measured from the pole of the mirror . 2 . Distances measured in the direction of incident light rays are taken as positive . 3 . Distances measured in opposite direction to the incident light rays are taken as negative . 4 . Distances measured above the principal axis are positive . 5 . Distances measured below the principal axis are negative .
Lateral inversion
In the image formed by a plane mirror the right side of the object ppears as left side and vise-versa . This phenomena is called lateral inversion .
When object is placed between pole and focus of a concave mirror , then its virtual , erect and magnified image is formed .
A convex mirror forms a virtual , erect and diminished image for all conditions of object .
The focal length of concave mirror is taken negative and for a convex mirror taken as positive .
Refraction of Light
The deviation of light rays from its path when it travels from one transparent medium to another transparent medium , is called refraction of light .