Question

A concave mirror of focal length f produces an image n times the size of the object. If the image is real, then the distance of the object from the mirror is...... options:- a) (n+1)*f. b) (n-1)/n*f. c) (n-1)*f. d) (n+1)/n*f
for more clearer view see the attachment...

Answer 1

Answer:

The distance of the object from the mirror is $\dfrac{n+1}{n}f$

d is correct option.

Explanation:

Given that,

Focal length = f

We have given,

$\dfrac{size\ of\ image}{size\ of\ object}=n$

In case of a concave mirror , if the image is real then it must be inverted

So, The magnification is

$m=-n=\dfrac{-v}{u}$

$m=n=\dfrac{v}{u}$

Using mirror formula,

$\dfrac{1}{u}+\dfrac{1}{v}=\dfrac{1}{f}$

$1+\dfrac{u}{v}=\dfrac{u}{f}$

$1+\dfrac{1}{n}=\dfrac{u}{f}$

$u = \dfrac{n+1}{n}f$

Hence, The distance of the object from the mirror is $\dfrac{n+1}{n}f$

Answer 2

Answer:

Explanation:

Here is it's answer,

Hope you will understand very easily.