Question

An object is placed at a distance of $f/2$ from a convex lens. The image will be

• A. At one of the foci, virtual and double its size
• B. At $3f/2$, real and inverted and erect
• C. At $2f$, virtual and inverted
• D. At $f$, real and inverted

Answer 1

The correct option is A At one of the foci, virtual and double its size

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

$\Rightarrow \frac{1}{v}-\frac{1}{\left(\frac{-f}{2}\right)}=\frac{1}{f}$

$\Rightarrow \frac{1}{v}=\frac{1}{f}-\frac{2}{f}=\frac{-1}{f}$

$\Rightarrow v=-f$

Hence,

option $\left(A\right)$ is correct answer.