Electron microscopes
- Created by: Steff06
- Created on: 29-03-16 12:21
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- Electron microscopes
- Electron microscopes produce a beam of electrons which have a wavelength of 0.004nm.
- Resolution of electron microscopes = 0.2nm
- Electron microscopes use MAGNETS instead of lenses to focus the beam of electrons onto the specimen. Image produced from the beam is projected onto a screen to make a black and white image (electron micrographs).
- TRANSMISSION electron microscope (TEM): Electron beam passes through a thin prepared sample. 2D image produced. Magnification possible = x500,000
- SCANNING electron microscop (SEM): Beam is directed onto sample but does NOT pass through - they are 'bounced off'. 3D image produced. Magnification possible = x100,000
- Advantages of electron microscopes:
- Resolution = 0.2nm which is better than a light microscope.
- Can be used to produce more DETAILED images of the organelles inside cells.
- SEM produces 3D images that can reveal detail of tissue arrangements, which is not possible using light microscope.
- Disadvantages of electron microscopes:
- Samples have to be placed in a VACUUM as electron beams are deflected by air molecules.
- Electron microscopes are extremely EXPENSIVE.
- Preparing samples and using an electron microscope require a high degree of SKILL and TRAINING.
- Colour can be added after producing a final image using specialised computer software which will provide false colour.
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