Question

A man standing in front of a concave spherical mirror of radius of curvature 120 cm sees an erect image of his face four times its natural size. Then the distance of the man from the mirror is –

• A. 180 cm
• B. 300 cm
• C. 240 cm
• D. 45 cm

Answer 1

Answer: (D)

45 cm

Answer 2

m = , m = + 4

f = $\frac { - 120 } { 2 }$ = – 60cm

\ + 4 = $\frac { - 60 } { - 60 - u }$ \ – 60 = – 240 – 4u

\ 4u = – 180 \ u = – 45 cm