Question

Find the position and nature of the image formed by the concave mirror of focal length $20\text{cm}$, if the object $O$ is placed at a distance $30\text{cm}$ from the pole.

• A. $-60\text{cm}$, Virtual image
• B. $+60\text{cm}$, Real image
• C. $-60\text{cm}$, Real image
• D. $+60\text{cm}$, Virtual image

Answer 1

The correct option is C $-60\text{cm}$, Real image

Given:
$u=-30\text{cm}$
$f=-20\text{cm}$
So, $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
$\Rightarrow \frac{1}{v}-\frac{1}{30}=\frac{-1}{20}$
$\Rightarrow \frac{1}{v}=\frac{-1}{60}$
$\Rightarrow v=-60\text{cm}$
As the image is formed on the same side of the concave mirror, the image is real.