Bacteria are difficult to see with a bright-field compound microscope for several reasons: They are small: In order to see their shape, it is necessary to use a magnification of about 400x to 1000x. The optics must be good in order to resolve them properly at this magnification.
Similarly one may ask, what can be seen at 400x magnification?
The compound microscope typically has three or four different magnifications - 40x, 100x, 400x and sometimes 1000x. At 40x magnification you will be able to see 5mm. At 100x magnification you will be able to see 2mm. At 400x magnification you will be able to see 0.45mm, or 450 microns.
Which kind of microscope is needed to view a virus?
Most bacteria can be seen with a light microscope (usually about 100x magnification). Viruses are considerably smaller, as they are merely nucleic acid surrounded by a protein shell as opposed to an entire living cell. Viruses typically range from 20-400 nm, meaning you need an electron microscope to see them.
What is 40x magnification?
To figure the total magnification of an image that you are viewing through the microscope is really quite simple. To get the total magnification take the power of the objective (4X, 10X, 40x) and multiply by the power of the eyepiece, usually 10X.