Microscopy
- Created by: chrislewis0411
- Created on: 22-04-15 09:24
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- Microscopy
- Microscopes produce a magnified image of a sample
- Magnification = how much bigger the image is than the specimen
- I = A x M (Image Size = Actual Size x Magnification)
- Resolution = how well a microscope distinguishes between two points that are close together
- Magnification = how much bigger the image is than the specimen
- Two Types of Microscopes
- 1) Light Microscopes
- Use Light
- They have lower resolution
- Maximum = 0.2 micrometers
- Maximum Magnification = x1500
- 1) Light Microscopes
- Staining
- Samples stained as a result of specimen being transparent
- Electrons pass straight through it
- For LIght Microscopes use dye
- Common stains are methylene blue and eosin
- Stain is taken up by some parts of the specimen more than others
- Contrast makes the different parts show up
- Stain is taken up by some parts of the specimen more than others
- Common stains are methylene blue and eosin
- For Electron Microscopes
- Objects are dipped in solution of heavy metals e.g. lead
- Metal ions scatter electrons
- Gain Contrast
- Metal ions scatter electrons
- Objects are dipped in solution of heavy metals e.g. lead
- Samples stained as a result of specimen being transparent
- Microscopes produce a magnified image of a sample
- 2) Electron Microscopes
- Use electrons
- Higher resoclution, so giove more detailed images
- Two Types of Microscopes
- 1) Light Microscopes
- Use Light
- They have lower resolution
- Maximum = 0.2 micrometers
- Maximum Magnification = x1500
- 1) Light Microscopes
- Two Types
- TEM - Transmission
- Use Electromagnets to focus a beam of electrons
- Electrons transmitted through specimmen
- Denser parts absorb more electrons, makes them look darker
- Electrons transmitted through specimmen
- Advantege - provide high resolution images
- Bad as they can only be used on thin specimens
- Use Electromagnets to focus a beam of electrons
- SEM - Scanning
- Scan a beam of electrons across specimen
- Knocks off electrons already on specimen
- Advantages - images produced show the surface of the specimen and can be in 3D
- Give lower resolution than TEM
- Scan a beam of electrons across specimen
- TEM - Transmission
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