Question

Focal length of a concave mirror is f. The distance from its focal point to theobject is P.
Find the ratio of heights of image.​

Answer 1

As per the sign convention for mirror, the focal length is taken as negative as it is measured opposite to the direction of light. Hence, focal length f = -f. The distance of the object from the principal focus is p. Hence, the distance of object from the mirror [ u ] = p+ f.