A 10 mm long all pin is placed vertically in front of a concave mirror. A 5 mm long image of the all pin is formed at 30 cm in
front of the mirror. The focal length of this mirror is
(a) – 30 cm
(c) – 40 cm
(b) – 20 cm
(d) – 60 cm




So, the correct answer is (b)

Go Ad-free
Maninder Singh's photo - Co-founder, Teachoo

Made by

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo