Most animal cells range in size from 0.01 to 0.05 mm, and plant cells from 0.01 to 0.10 mm.
The human eye can see objects as small as around 0.05 mm. Therefore a microscope is needed to see cells in detail.
Microscopes magnify the image of a specimen - cells, tissues or other structures - so that it appears larger. The type of microscope most used in schools is a compound microscope.
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.
Magnification of the microscope = magnification of eyepiece × magnification of objective
So, if the magnification of an eyepiece is ×10 and the objective is ×4, the magnification of the microscope is:
magnification of eyepiece × magnification of objective = 10 × 4 = 40
If the magnification of an eyepiece is ×10 and the objective is ×40, what is the magnification of the microscope?
10 × 40 = ×400
Microscopes use lenses to magnify the image of a biological specimen so that it appears larger.
The formula to calculate magnification is:
The formula shown in a magnification triangle: