(a) – 30 cm
(b) – 20 cm
(c) – 40 cm
(d) – 60 cm
Answer: (b) – 20 cm
Explanation: In this case, the focal length of the concave mirror is – 20 cm.
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
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