Question

A simple microscope has a focal length of $25\text{cm}$. The maximum and minimum magnifying powers, that can be obtained are, respectively -

• A. $3$ and $1$
• B. $2$ and $1$
• C. $3$ and $2$
• D. $4$ and $2$

Answer 1

The correct option is B $2$ and $1$

The magnifying power is maximum, when the image is formed at near point $i.e.D=25\text{cm}$.

So,

$m_{\text{max}}=1+\frac{D}{f}=1+\frac{25}{25}=2$

The magnifying power is minimum, when the image is formed at infinity.

$m_{\text{min}}=\frac{D}{f}=\frac{25}{25}=1$

Therefore, the maximum and minimum magnifying powers, that can be obtained are, respectively, $2$ and $1$.

Hence, option $\left(B\right)$ is the correct answer.