Question

An object is placed at a distance $u$ from a simple microscope of focal length $f$. The angular magnification obtained depends

• A. on $f$ but not on $u$
• B. on $u$ but not on $f$
• C. on $f$ as well as $u$
• D. neither on $f$ nor on $u$

Answer 1

The correct option is A on $f$ but not on $u$

Angular magnification of a simple microscope is given by,

$m=\frac{D}{u}$

Here, $D$ is the least distance of distinct vision.


From Len's equation,

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

$\Rightarrow \frac{1}{f}=\frac{1}{-D}-\frac{1}{-u}$

$\Rightarrow m=\frac{D}{u}=1+\frac{D}{f}$

Therefore, angular magnification depends only on $f$.

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

Why this question : Angular magnification depends only on the focal length of the lens.