microscopy

• Microscopy


  The use of microscopes
• How light microscopes work

  1. Light from the room hits the mirror

  2. Light reflected upwards through the object

  3. Light passes through the objective lens

  4. Light passes through the eyepiece lens

  5. Light enters the eye
• Object


  The real object or sample that you're looking at
• Image


  The image that we see when we look down the microscope
• Magnification


  How many times larger the image is than the object
• Magnification = image size / object size
• Resolution


  The shortest distance between two points on an object that can still be distinguished as two separate entities
• Higher resolution


  More details can be seen, less blurry the image
• Light microscopes


  Microscopes that use light, small, easy to use, relatively cheap
• Resolution of light microscopes

  Limited to 0.2 micrometers, any details less than 0.2 micrometers apart will appear blurry
• What light microscopes can be used to see

  • Individual cells like onion cells
• Electron microscopes


  Really big, very expensive, hard to use, only used by scientists in laboratories
• Resolution of electron microscopes

  Maximum resolution of 0.1 nanometers, 2000 times better than light microscopes
• What electron microscopes can be used to study

  • Sub-cellular structures like mitochondria
• Electron microscopes can give images with much higher magnifications without going blurry
• Units of length


  • Nanometers
  • Micrometers
  • Millimeters
  • Meters
  • Kilometers
• Each unit is 1,000 times bigger or smaller than the one next to it
• Converting between units


  1. Divide by 1,000 to convert to a larger unit

  2. Multiply by 1,000 to convert to a smaller unit
• Atoms range from 0.1 to 0.5 nanometers across
• Animal and plant cells are 10 to 100 micrometers across
• The naked eye can see down to about 100 micrometers
• Light microscopes can see down to about 500 nanometers
• Electron microscopes can see down to about 0.1 nanometers
• Centimeters


  10 millimeters, 100 centimeters in a meter
• Converting centimeters


  1. Divide by 100 to get meters

  2. Multiply by 10 to get millimeters
• magnification equation 


  image size/real size
• slide preparation (practical)

  1. add a drop of water to the middle of a clean slide
  2. cut up an onion and seperate it out into layers, use tweezers to peel off some epidermal tissue from the bottom of one of the layers
  3. Using the tweezers, place the epidermal tissue into the water on the slide.
  4. Add a drop of iodine solution(stain), Stains are used to highlight objects in a cell by adding colour to them.