Most animal cells range in size from 0.01 mm - 0.05 mm and plant cells from 0.01 mm - 0.10 mm.
The human eye can see objects as small as around 0.05 mm. We therefore need a microscope to see cells in any detail.
Microscopes magnify the image of a specimen - cells, tissues of other structures - so that it appears larger. The type of microscope used in the school laboratory is a compound microscope. Compound microscopes can have a built-in light source or a mirror which reflects light from a light source to illuminate the specimen.
In most microscopes, there is a choice of objective lenses to use. Magnification can therefore be varied according to the size of the specimen to be viewed and the level of detail required.
The magnification of a lens is shown by a multiplication sign followed by the amount the lens magnifies, eg ×10.
The total magnification can be calculated by multiplying the magnifying powers of the two lenses together.
So, if the magnification of an eyepiece lens is ×10 and the objective lens is ×4, the total magnification of the microscope is:
magnification of eyepiece lens × magnification of objective lens = 10 × 4 = ×40.
If the magnification of an eyepiece lens is ×10 and the objective lens is ×40, what is the total magnification of the microscope?
It is 10 ×40 = ×400.