A `10 mm` long awl pin is placed vertically in front of a concave mirror. A `5 mm` long image
Channel: Doubtnut
Date: 2020-07-26

A `10 mm` long awl pin is placed vertically in front of a concave mirror. A `5 mm` long image of the awl pin is formed at `30 cm` in front of the mirror. The focal length of this mirror is