Question

The image formed by a convex mirror of focal length 30 cm is a quarter of the size of the object. The distance of the object from the mirror is –

• A. 30 cm
• B. 90 cm
• C. 120 cm
• D. 60 cm

Answer 1

Answer: (B)

90 cm

Answer 2

f = + 30 cm ; m = +$\frac { 1 } { 4 }$

u = $\left( \frac { \mathrm { m } - 1 } { \mathrm {~m} } \right) \mathrm { f }$ =$\left( \frac { \frac { 1 } { 4 } - 1 } { \frac { 1 } { 4 } } \right) 30$

= –3 × 30 = – 90 cm