Question

A virtual erect image in a concave mirror is represented, in the given figure, by

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

For virtual erect image by a concave mirror.


$v=+ve,u=-ve,f=-ve$

$\frac{u}{f}=+ve,\frac{v}{f}=-ve$

As mirror formula,

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

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

$-\frac{f}{v}=\frac{f}{u}-1$

or $\frac{f}{v}=1-\frac{f}{u}$

In order to find the plot, Let $y=\frac{v}{f}$

and $x=\frac{u}{f}$

$\frac{1}{y}=1-\frac{1}{x}$

$\Rightarrow y=\frac{x}{x-1}$

${lim}_{x\to 0}y=0$

${lim}_{x\to 1-}y=\infty$

Hence, only option $D$ matches the limits criteria.