Light and Electron Microscope.

Authors Avatar

Biology

Light and Electron Microscope

  • The light microscope (like the ones commonly used in schools) relies on light being reflected onto a mirror, which shines through a very small, thin specimen. Often this will be a section through some living cells or tissue. The section must be thin enough to allow the light rays to pass through it and then onto the eye of the person using the microscope. Glass lenses focus the light rays.
  • The electron microscope is a much more powerful and expensive piece of kit. Instead of light, it uses a beam of electrons which are fired at a very thin section of material. The electrons scatter when they hit the specimen and affect a photographic plate so that a black and white image of the specimen is formed. These microscopes are harder to use, but the enable you to look at really tiny objects, even molecules.
Join now!

The main comparisons of a light microscope (LM) and electron microscope (EM) are outlined below;

  • Resolution. This is the ability to distinguish between 2 separate points. The distance is half the wavelength of the medium used. For light then the effective resolution is 200nm, anything smaller cannot be seen clearly. The electron microscope has a resolution of 0.5 nm, which means that all the organelles and ultrastructure of cells can be viewed.
  • Magnification (X). This is the number of times larger an image can be made compared to the real object. A LM can achieve a magnification of 1500 ...

This is a preview of the whole essay