Simple Microscope - Practice Questions & MCQ

Magnifying power: It is defined as the ratio between the dimensions of the image and the object.  

Magnifying power of an optical instrument is given by,

$
m=\frac{\text { Visual angle with instrument }(\beta)}{\text { Visual angle when object is placed at least distance of distinct vision }(\alpha)}
$
 

Simple Microscope

• It is a single convex lens of lesser focal length.
• Also called magnifying glass or reading lens.

Case 1: Magnification's, when the final image is formed at $D$ and $\infty$.

$
\begin{aligned}
& \text { (i.e. } m_D \text { and } m_{\infty} \text { ) } \\
& m_D=\left(1+\frac{D}{f}\right)_{\max \text { and }} \\
& m_{\infty}=\left(\frac{D}{f}\right)_{\min }
\end{aligned}
$

Case 2: If lens is kept at a distance a from the eye then

$
\begin{aligned}
& m_D=1+\frac{D-a}{f} \text { and } \\
& m_{\infty}=\frac{D-a}{f}
\end{aligned}
$