microscopes

• label the diagram

  A) eyepiece

  B) body tube

  C) arm

  D) revolving nosepiece

  E) objective lenses

  F) stage

  G) coarse adjustment

  H) fine adjustment

  I) base

  J) stage clips

  K) condenser

  L) light source

  
• resolution


  how clearly we can determine two points. the higher the resolution the greater the detail
• magnification


  the number of times larger an image appears, compared with the size of the object
• light microscope

  • light travels from the light source through a condenser lens before passing through the specimen
  • the objective lens magnifies the image
  • it is magnified again by the occular lens
  • in order to focus the image the distance between the 2 main lenses is altered
• electron microscopes


  • electron microscopes use beams of electrons instead of light rays
  • higher resolution
  • this means we can magnify objects to a greater extent and still see a clear image
• 2 types of electron microscopes

  • TEM - transmission electron miscroscopes, electrons are passed through a thin specimen
  • SEM - scanning electron microscope, electrons are bounced off the surface of an object
• transmission electron microscope


  • gives high resolution images
  • gives high magnification images
  • can only be used on thin specimens
  • can only be used on non-living specimens
  • images are in black and white (colour added on a computer)
• scanning electron microscope


  • gives high resolution images
  • gives high magnification images
  • can be used on thick specimens
  • 3D images
  • can only be used on non-living specimens
  • images are in black and white (colour added an a computer)
  • gives lower resolution then TEM
• artefacts


  damage caused by the preparation process which could be interpreted as part of the structure