Question

A convex mirror of focal length f forms an image which is 1/n times the object. The distance of the object from the mirror is

• A. (n – 1) f
• B. $\left( \frac { n - 1 } { n } \right) f$
• C. $\left( \frac { n + 1 } { n } \right) f$
• D. (n + 1) f

Answer 1

Answer: (A)

(n – 1) f

Answer 2

By using $m = \frac { f } { f - u }$

Here $m = + \frac { 1 } { n }$ , $f \rightarrow + f$

So, $+ \frac { 1 } { n } = \frac { + f } { + f - u }$ $\Rightarrow$ $u = - ( n - 1 ) f$