microscopy

• Parts of a microscope

  1. eyepiece lense (x10 magnification)
  2. focus knob
  3. fine focus knob
  4. objective lenses
  5. slide
  6. stage
  7. mirror
• set up

  make sure there is a light source nearby reflecting off mirror i there isn't a light built in.
• preparing slide

  • carry slide by edges to not get finger prints on it
  • drop water onto the centre
  • cut onion into layers and peel off some spidermal tissue with forceps
  • place tissue onto water making sure it is flat and not folded
  • add a drop of iodine solution to highlight and stain subcellular structures
  • place glass cover over onion tissue by standing it upright on slide before carefully tilting to avoid air bubbles
  • wipe away excess iodine with paper towel
• using microscope

  • clip prepared slide on to stage
  • select lowest powered objective lens and get down so microscope is at eye level
  • use coarse focus knob to adjust the lens to as far down as you can go then look in the eyepiece and use fine focus knob until image comes into focus
  • then repeat this process with higher magnifications until you get a clear image
  • measure the field of view by placing a clear ruler on the stage over the hole and count how many mm marking you can see then times this by 1000 to get the distance in micrometers
• Drawing observations

  • draw what you see with a sharp pencil
  • drawing should occupy at least half available space with clear unbroken lines
  • no colouring or shading
  • subcellular structures should be in proportion
  • include title of what you are observing, magnification, field of view and real size
  • label subcellular structures using straight uncrossed lines
• magnification formula

  magnification = image size/real size