Microscopy

• Light microscopy

  • Eyepiece lens - looked through to see the image. Magnifies the image
  • Objective lens - magnifies the image. (Usually x4, x10 and x40)
  • Stage - Supports the slide
  • Clip - Holds the slide in place
  • Handle - To carry the microscope
  • Lamp - Shines light through the slide so the image can be seen more safely
  • Focusing knobs - moves the stage up and down to bring the image into focus

  
• Preparing a microscope investigation

  1. Peel a thin slice of the specimen
  2. Using tweezers, place you specimen on the slide
  3. Add a drop of stain if needed (eosin stains cytoplasm, methylene blue stains DNA)
  4. Place a cover slip on the specimen
  5. Clip the slide onto the stage
  6. Select the lowest powered objective lens and use the coarse adjustment lens to move the stage to just below the objective lens
  7. Then move the stage down (using the coarse adjustment knob) until the specimen is just in focus
  8. Then, still looking down the eyepiece, adjust the focus with the fine adjustment knob
  9. If you need to see with a higher magnification, swap to a higher powered lens and refocus

  
• Magnification = image size / real size
• Total magnification = eyepiece lens magnification x objective lens magnification
• Electron microscopes

  Pros:

  • More detail (higher magnification, higher resolution)
  • Can see smaller things

  Cons:

  • Expensive
  • Very big