We use microscopes to look at very small things. The microscope magnifies the image so that it appears larger than it would with just our eyes.

Calculating the magnification of an image

Microscopes use lenses to magnify the image of a biological specimen so that it appears larger.

The magnification of a lens on a microscope is shown by a multiplication sign followed by the amount the lens magnifies, eg ×10.

The formula to calculate magnification is:

\text{magnification} = \frac{\text{size of image}}{\text{real size of object}}


If the size of a cell seen down the microscope is 5 mm and the real size of the object is 0.005 mm, what is the magnification?

= 5 ÷ 0.005

= ×1,000

The magnification is therefore ×1,000.