Microscopes

Comparing light and electron microscopes

Customize Share

Play

Show all Difficult Familiar Mastered Starred

How do microscopes give us a magnified image of an object?

By using 2 lenses - they eye piece lens and the objective lens.
How is the total magnification calculated?

By multiplying both together. E.g: if the eye piece is x40 and the objective lens is x100 the total magnification is 4000.
Light rays

Light rays have a long wave length (400-700nm). This is fine for studying human hair, which is about 100 times bigger than the wavelenght of light, but not for a bacterium that is 200nm in length or a protein molecule that is just 10nm.
Seeing detailed objects

If you want to see in detail objects that are smaller than the wavelength of light, you need to use electrons.
Electrons

Electrons have a very short wavelength (1nm) which allows us to see objects much smaller than the wavelenght of light.
Electron microscope

In an electron microscope, a beam of electrons is used instead of light rays. When the electrons reach the specimen, some pass through and some bounce off - the electrons that pass through are detected and displayed as an image on a flourescent screen.
Electron microscope magnification

Electron microspcopes have much higher magnification and resolving power (the ability to see 2 points as being separate) than a microscope. This means that cells can be studied in much finer detail and biologists can now see many more sub-cellular structures.