Electron Microscopes and all that jazz.

The electron microscope:
Electron microscopes work by using a beam of electrons, instead of light, as they have a shorter wavelength and with will give them a higher resolving power.
Differences between Scanning Electron Microscope and Transmission Electron Microscope are the TEM sends a beam of electrons through a thin section of the specimen. Parts of it absorb the electrons and appear dark, and parts of it appear light, as they allow the electrons to pass through and an image is produced. With the SEM, A thin section is not needed, as the electrons are not made to penetrate the sample. Instead, the electrons are directed onto the surface, and go over the surface in a pattern, gaining a 3D image, because of the way the electrons end up scattered over the contours of the surface. The SEM, however, has a lower resolution then the TEM.
The limitations of the TEM are that you have to have a thin sample, and it must be in vacuum, so no living specimens can be used. The image may contain artefacts, things that enter through the prep process, which wouldn’t be in the real cell. Also, there is a complex staining process, but the image is still only in black and white.
The limitations of the SEM are the same as the limitations of the TEM, (staining process, artefacts, in a vacuum), but it doesn’t have to be extremely thin, as the electrons are on the surface and don’t penetrate the sample.

1) The electron microscope is able to resolve objects better then a light microscope, as it has a shorter wavelength, which means it have a greater resolving power.
2) The specimens in an electron microscope must be in near vacuum to be viewed effectively, as the electrons can be absorbed my molecules in the air, and without the electrons, a picture could not be created.
3) A light microscopes resolution isn’t very good, therefore it could probably see a bacterium or a plant cell, the TEM has a resolution on 0.1nm, so you could see all of them with it (Plant cell, DNA Molecule, Virus, Actin Molecule, and a Bacterium.) The SEM has a resolving power 20nm, so you could see the plant cell, the virus and the bacterium.
4) The resolving power of an electron microscope cannot always be achieved as the preparation process of the sample can be quite problematic, and can cause difficulties.
5) Image = 25mm, Actual = 5um, Magnification =25000/5 = x5000