Question

A $6.0mm$-diameter microscope objective has a focal length of $9.0mm$. What object distance gives a lateral magnification of $-40$?

Short answer

The object distance is $4mm$.

Step-by-step solution

Given Information.

We have given that:

Diameter= $6.0mm$,

focal length=$9.0mm$ .

We need to find object distance which gives a lateral magnification of $-40$.

Equation.

$m_{obj}=40$

$L=160mm$

Object is not close to the focal point $S\approx f_{obj}$.

Approximation, lateral magnification is given:

$m_{obj}=-\frac{1}{f_{obj}}$.

Calculation

$L=160mm$represent microscope tube length.

Let us find the value of $f_{obj}$.

$f_{obj}=\frac{L}{m_{obj}}$

$f_{obj}=\frac{160mm}{40}$

$f_{obj}=4mm$.