![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](https://www.gkseries.com/blog/wp-content/uploads/2022/05/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.png)
Q. 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. – 30 cm
B. – 20 cm
C. – 40 cm
D. – 60 cm
Answer: – 20 cm