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  • Microscopes
    • Light Microscope
      • Uses a number of lenses to produce an image that can viewed directly at the eyepieces
      • Light passes from a bulb uder the stage, through a condenser lens, then through the specimen
      • This beam of light is focused through the objective lens, then through the eyepiece lens
      • Have a number of different objective lenses
        • Four objective lenses are present: x4, x10, x40 and x100. (The x100objective is an oil immersion lens
      • The eyepiece lens then magnifies the image again. (usually x10)
      • The total magnification can be found by multiplying the objective magnification by they eyepiece magnification
      • Advantages - capable of x1500 magnification, a wide range of specimens can viewed
      • Disadvantages - only 200nm resolution
    • Resolution - is thedegree to which it is possible to distinguish between two objects that are very close together.
      • The higher the resolution, the greater the detail you can see.
    • Magnification - is the degree to which the size of an image is larger than the object itself.
      • I=A/M
    • Electron Microscopes
      • Types
        • Transmission Electron Microscope
          • The electron beam passes through a very thin prepared sample
          • Electrons pass through the denser parts of the sample less easily, so givving some contrast
          • Produces 2D images
          • Possible magnification is x500,000
        • Scanning Electron Microscope
          • The electron beam is directed onto a sample. The electrons don't pass through the specimen.
          • Electons bounce off sample
          • Produces a 3D image
          • Possible magnification is x100,000
      • Advantages - resolution is 0.2nm, more detailed images, produces 3D images
      • Disadvantages - smaples have to be in a vaccuum, extremely expensive, preparing samples require a high degree of skill and training
  • Advantages - resolution is 0.2nm, more detailed images, produces 3D images


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