Microscopes

• Microscopy


  The use of microscopes to study small objects and organisms
• Microscopes

  • They magnify images (make them look bigger)
  • They increase the resolution of an image (how well it distinguishes between two points that are close together)
• Light microscopes


  They work by passing light through the specimen and can be used to study living cells.
• Electron microscopes


  They use electrons rather than light
• Electron microscopes have a higher magnification and resolution than light microscopes
• Electron microscopes allow us to see much smaller things in more detail like the internal structure of mitochondria and chloroplasts, although they can't be used to view living cells
• How to view a specimen using a light microscope

  1. Take a thin slice of the specimen

  2. Place the specimen on a slide with a drop of water

  3. Add a stain if the specimen is colourless

  4. Place a cover slip over the specimen

  5. Select the lowest-powered objective lens

  6. Use the coarse adjustment knob to move the stage so the specimen is just underneath the objective lens

  7. Adjust the focus with the fine adjustment knob until the specimen is in focus

  8. Swap to a higher-powered objective lens to see the specimen with greater magnification
• How to create a scientific drawing of a specimen

  1. Draw outlines of the main features using clear, unbroken lines

  2. Make sure the drawing takes up at least half the space and keep the parts in proportion

  3. Label the important features with straight lines that don't cross over each other

  4. Include the magnification used and a scale
• Magnification

  How many times bigger the image is compared to the real size of the specimen
• Equation for total magnification if you know the power of the lenses:

  total magnification = eyepiece lens magnification x objective lens magnification
• Equation for magnification if you don’t know which lenses were used:

  magnification = image size/real size
• Units: Standard form:

  millimetre (mm). x 10 to the power of -3 m

  micrometre x 10 to the power of -6 m

  nanometre (nm). x 10 to the power of -9 m

  picometre (pm). x 10 to the power of -12 m

  Conversions:

  millimetre to micrometre = x1000

  micrometre to millimetre = /1000

  (same for others)
• Electron microscopes were made after light microscope.

  electron - 1930s

  light - 1590s