Electron microscopes

• What type of radiation does an electron microscope use?

  A beam of electrons
• What is the maximum magnification of an electron microscope?

  2,000,000x
• What is the maximum resolution of an electron microscope?

  0.1 nm
• Why do electron microscopes have a higher resolution than light microscopes?

  Because electrons have a smaller wavelength than light
• Why must specimens be dead in electron microscopes?

  Because they must be in a vacuum
• Why is a vacuum required in electron microscopes?

  To prevent interference with the electron beam
• What does a Transmission Electron Microscope (TEM) use to focus the electron beam?

  Electromagnets
• What does a TEM work?

  The beam of electrons is transmitted through a specimen
• Why do denser parts of a specimen look darker in a TEM image?

  Because they absorb more electrons
• What can TEM images show?

  Internal structures of organelles
• Can TEMs be used on thick specimens?

  No, only very thin specimens/cross sections
• How does a Scanning Electron Microscope (SEM) form an image?

  By scanning a beam of electrons over the specimen
• What type of image does an SEM produce?

  3D image
• What can SEMs show on a specimen?


  The surface of the specimen
• How does the resolution of an SEM compare to a TEM?


  Lower resolution than TEM
• Which type of electron microscope is better for internal details?

  TEM
• Which type of electron microscope is better for surface details?

  SEM