Question

According to the "New Cartesian Singh Convention" for mirrors, what sign has been given to the focal length of:

(i) a concave mirror?
(ii) a convex mirror?

Answer 1

(i) The sign given to the focal length of a concave mirror (according to the New Cartesian Sign Convention) is negative. This is because the focus of a concave mirror is in front of the mirror, on the left side.
(ii) The sign given to the focal length of a convex mirror (according to the New Cartesian Sign Convention) is positive. The is because the focus of a convex mirror is behind the mirror, on the right side.