Question

A person looks at his image, which is 3 times the original size, in a mirror. If radius of curvature of the mirror is 36 cm, find his distance from the mirror?

• A. 12 cm
• B. 18 cm
• C. 6 cm
• D. 4.5 cm

Answer 1

The correct option is A 12 cm

m = +3
f = -18 cm
$m=\frac{f}{f-u}=\frac{f}{f-(-x)}$
$3=\frac{-18}{(-18+x)}=\frac{-18}{x-18}$
x - 18 = -6
x = 12 cm