Question

A convex mirror has a focal length f. An object is placed at a distance f/2 in front of it from the pole. The mirror produces an image at

(a) infinity

(b) f

(c) 2f

(d) f/3

Answer 1

Correct option is (d) f/3

Since, \(\frac 1v + \frac 1u = \frac 1f\)   (mirror formula)

⇒ \(\frac 1v= \frac 1f - \frac 1u\)    \(\left[\because u =\frac{-f}2\right]\)

\(= \frac 1f + \frac 2f\)

\(\therefore \frac 1v = \frac 3f\)

⇒ \(v = \frac f3\)