A card divided into squares each of size \(1\ \mathrm{mm^2}\) is viewed through a magnifying glass of focal length \(10\) cm which is held close to the eye. The distance at which the lens is to be placed from the card to view the squares with maximum possible magnification is
Show Hint
A simple microscope produces maximum magnification when the image is formed at the least distance of distinct vision.
Use
\[
\boxed{
v=-25\text{ cm}
}
\]
and apply
\[
\boxed{
\frac1f=\frac1v-\frac1u.
}
\]