Q

An object is 20 cm in front of a concave mirror of focal length 10 cm. What is the correct signed image distance?

RRB Group-D 13/08/2026 (9:00 AM - 10:30 AM) 2026
✓ Answer: A -20 cm
With u = -20 cm and f = -10 cm, 1/v = -1/10 + 1/20 = -1/20, so v = -20 cm.