What sign conventions are used for reflection from a spherical mirror?

Hint:Sign conventions refers to the negative and the positive sign that we must use for the calculation of any variable equation. Spherical mirror refers to those mirrors which are a part of a bigger circle in which either the curved surface or the bulged surface acts the reflection surface.

Complete answer:
Reflection refers to the change in the direction of propagation of light ray when they strike a surface.The sign convention method that are used for reflection of light ray from a spherical mirror is-
(i) The object must be placed to the left side of the spherical mirror.
(ii) All the distances which are parallel to the principal axis must be calculated from the pole of the mirror which is considered to be the origin.
(iii) The distances which are measured to the right side of the origin or pole of the mirror are considered to be positive whereas the distances which are at the left side of the origin are considered to be negative.
(iv) The distances which are measured perpendicular to and above the principal axis are considered to be of positive sign.
(v) The distances which are measured perpendicular to and below the principal axis are given a negative sign.

Note:It must be noted that sign conventions are very much crucial for mathematical calculations without which you aren't able to get the accurate calculation. Spherical mirrors are of two types, convex and concave both follow the same sign convention rule. Not only spherical mirrors, the same sign convention is applicable in case of plane mirrors too.