Microscopes

• Microscope


  A scientific instrument used to see magnified images of things the naked eye cannot see.
• Using Units


  1 kilometre (km) = 1000 metres (m)

  1 metre (m) = 100 centimetres (cm)

  1 centimetre (cm) = 10 millimetres (mm)

  1 millimeter (mm) = 1000 micrometres (μm)

  1 micrometer (μm) = 1000 nanometres (nm)

  A Nanometer (nm) =0.000000001 metres (1x10⁻⁹m)
• A Light Microscope

  Diagram

  A) Eyepiece

  B) Objective lens

  C) Stage

  D) Slide

  E) Light

  F) Fine focus

  G) Coarse focus

  
• Light Microscopes

  • The first light microscopes were developed in the mid - 17th century and are still widely used to look at cells.
  • Light Microscopes use a beam of light to form an image of an object
  • The best light microscopes can magnify around x2000
  • School microscopes only magnify several hundred times and are relatively cheap
  • Can also be used anywhere and can magnify live specimens.
• • Objective lens: Magnifies the specimen, allowing you to see it in more detail.
  • Coarse adjustment: Brings the specimen into general focus by moving the stage or lenses.
  • Fine adjuster: Sharpens the focus to give a clear, detailed view of the specimen.
• Electron Microscopes

  The invention of the electron microscope in the 1930s allowed biologists to see and understand more about the subcellular structures inside cells
• Electron Microscopes

  These instruments use a beam of electrons to form an image and can magnify objects up to around 2000000 times.
• Electron Microscope

  Transmission electron microscopes give 2D images with very high magnification and resolution.
• Electron Microscope

  . Scanning electron microscopes give dramatic 3D images but lower magnifications (Figure 3).

  
• Electron Microscope

  Electron microscopes are large, very expensive, and have to be kept at special temperature, pressure, and humidity controlled rooms.
• To figure out the magnification of a light microscope.

  magnification of eyepiece x magnification of objective lens
• Calculating the size of a real object

  Magnification = size of image / size of real object

  
• Resolution is the ability to distinguish between two separate points and it is the resolving power of a microscope that affects how much detail it can show.
• Key Point

  
  

  • Electron microscopes magnify up to about 2:000000, and have a resolving power of around 0.2mm.
  • Magnification = size of image / size of real object
  • Light microscopes magnify up to about 2000, and have a resolving power of about 200 nm.