Microscopes

Microscopes

Total magnification = Object mag. x Eyepiece mag.
1. Magnification is the degree to which the size of an image is larger than the object itself.
Resolution is the degree to which 2 very close objects can be distinguished to see the details.
1. The higher the resolution, the greater the detail of a specimen.
LIGHT MICROSCOPES
1. max. resolution is 200nm
2. use objective lenses that can be rotated to view specimens at varying magnifications
3. max. magnification x1500
4. Preparation of Specimens:
  1. #1 Staining - chemicals bind to chemicals in/on specimen, allow specimen to be seen - some stains bind to specific cell structures
  2. #2 Sectioning - embed specimen in wax, cut sections without damaging their structure
5. can be used to view living organisms
  1. relatively cheap, can view natural colour of specimens, small and protable
ELECTRON MICROSCOPES
1. Generate a beam of electrons with a wavelength of 0.004nm. Use magnets to direct the beam. Must be viewed on a screen.
2. Can distinguish between objects 0.2nm apart.
3. max. resolution 0.1nm
4. max. magnification x500,000
5. Transmission Electron Microscopes
  1. beam passes through thin specimen, pass through less dense areas less easily
  2. 2D image
  3. x500,000 mag
6. Scanning Electron Microscopes
  1. electrons bounce off specimen
  2. 3D image
  3. x100,000 mag
7. specimen must be placed in a vacuum
  1. can only be used by highly trained personnel, only b&w images, can view cell ultrastructure, v. expensive

Resource summary

	Created by sophieisnotakise over 9 years ago