Question

A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature 36cm. The distance of the object from the mirror is

• A. 5 cm
• B. 12 cm
• C. 10 cm
• D. 20 cm

Answer 1

Answer: (B)

12 cm

Answer 2

m = + 3 (virtual)

f = – = – 18 cm

m = –

mu – mf = – f

u = f

= $\left( \frac { 3 - 1 } { 3 } \right)$ × – 18

= – $\frac { 2 } { 3 }$ × 18 = – 12 cm