types of microscope electron microscope an electron microscope

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Electron Microscope

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  • Types of microscope

  • Electron Microscope

  • An electron microscope

  • Magnification = The number of times the image has been enlarged by the microscope, bigger than the objects real actual size. LM max mag. = 1,500X, EM max mag. 500,000X

    Resolution (or Resolving power) =The ability of the microscope to distinguish clearly between 2 points that are extremely close together.

  • Figure 1.1 Magnification vs. Resolution

  • ResolutionThe Light Microscope has a resolving power of around 250nm (nanometers) which is the same as 0.25m (micrometers), so if two objects are closer than 0.25m they will not be detected as 2 clear points.The Electron Microscope has much better resolving power of around 1nm, which is the same as 0.001m, so it can detect much greater detail.

  • See my pdf notes comparing wavelenths of light and an electron beam

  • There are 2 different types of Electron Microscope:

  • Transmission electron microscope

    A transmission electron microscope produces 2D images from electrons which pass through the sample. An extremely thin specimen is needed.

  • Golgi body surrounded by mitochondria in a mouse myeloid cell

  • A plant cell

  • Scanning Electron Microscope

    A scanning electron microscope produces 3D images from electrons reflected off the samples surface.

  • Isolated mitochondria from bovine lymphocytes

  • Philonicus albiceps head

  • This cell is a type of skin cancer cell. The cell has been frozen and split open to reveal its nucleus (central red area). (Image: Anne Weston)

  • What next?Complete the comparison tables on the bottom of your Handbook p4 and the top of p5 booklet by circling the correct choices and crossing out the wrong ones - use textbook pages 43-45 to help.

    Now complete tasks found in the middle of handbook p5.

  • Units of measurement1m (1 metre) = 1000mm1mm = 1000m (micrometres)1 m = 1000 nm (nanometres)To convert mm to m multiply by 1000To convert m to mm divide by 1000When doing calculations you need to make sure that your measurements are in the same units.

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