With a concave mirrorr, an object is placed at a distance `x_(1)` from the principal focus, on the
Channel: Doubtnut
Date: 2020-01-19

With a concave mirrorr, an object is placed at a distance `x_(1)` from the principal focus, on the principal axis. The image is formed at a distance `x_(2)` from the principal focus. The focal length of the mirrorr is