Eloctron Microscope

An essay on Electron Microscopy
An essay on Electron Microscopy



An electron microscope (EM) shows the essential features of a cell. This uses an electron stream which is directed at the specimen. This invention was built in the 1930’s. The transmission electron microscope (TEM) has extremely high magnification and resolution properties. The reason why biologists need a high resolution is in able to see the specimen in more detail.



Feature
 

Electron microscope



Wavelength
 

Electron beam – 1.0 nm



Resolution
 

0.5 nm



Maximum useful magnification
 

X 250 000



Image
 

Black and white – colour enhanced

By computer



Specimens
 

Non-living



Advantages
 

Very high resolution- can see

Plenty of cell detail



Focused by
 

Magnets



Illumination
 

Electrons

            The way an image is formed on a electron microscope (EM) is by the electrons in an electron microscope (EM) are focused. Here the particles or the membranes in cells can be seen as separate objects if they are further apart than half of the wavelength of the beam of the electrons used. Electron microscopes have a high resolution because the electron beams have a shorter wave length. Also the other reason why biologists need a high resolution is in able to see the specimen in more detail.

            The table below gives information about an electron microscopy:









The development of electron microscope (EM) has had a huge impact on biology. Due to the fact that the resolution is so high on a electron microscopy that new cell structures have been discovered.

            The main disadvantage of having an electron microscope (EM) is that the electron beam must travel in a vacuum because, being so small, electrons are scattered when they hit air molecules. Therefore specimens have to be perpeared so that they retain their structure inside a...