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level: 3.2 The electron microscope

Questions and Answers List

level questions: 3.2 The electron microscope

QuestionAnswer
Two types of microscopes- Optical (light) - Election
Optical (light) microscopes- Uses light to form image - Max resolution - 0.2 micrometres - Can only see mitochondria and nucleus - Magnification - x1500 - Can be alive specimens
Electron microscopes- Uses electrons to form image - Higher resolution (electrons have shorter wavelength), Max - 0.0002 micrometres - Can see more organelles - Magnification - x1,500,000 - Have to be dead specimens
Two types of electron microscopes- Transmission electron microscopes (TEMs) - Scanning electron microscopes (SEMs)
Transmission electron microscopes (TEMs)- Uses electromagnets to focus beam of electrons, then transmitted through specimen - Denser part of the specimen absorb more electrons, makes them look darker
Advantages + disadvantages to TEMs- High resolution images than SEMs - Can only use thin specimens
Scanning electron microscopes (SEMs)- Scans a beam of electrons across specimen, knocks off electrons, which is gathered in a tube cathode ray tube - Image shows surface of specimen - Can be 3D
Advantages + disadvantages to SEMs- They can be used on thick specimens - Lower resolution images than TEMs