Question

explain the sign convention for measuring distances from mirror​

Answer 1

Answer:

Sign convention for spherical mirrors:

Object is always considered at the left of mirror

Distances measured along y-axis above the principal axis are taken as positive and that measured along y-axis below the principal axis are taken as negative.

Distances measured in the direction of the incident ray are taken as positive and the distances measured in the direction opposite to that of the incident rays are taken as negative.

All distances are measured from the pole of the mirror.

Sign convention for spherical lenses:

All distances measured above the principal axis are taken as positive. Thus, height of an object and that of an erect image are positive and all distances measured below the principal axis are taken as negative.

The distances measured in the direction of incident rays are taken as positive and all the distances measured in the direction opposite to that of the incident rays are taken as negative.

All distances on the principal axis are measured from the optic center.