Biology 2.1.1 Microscopes

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  • Created by: AabirA
  • Created on: 03-04-17 08:14
Magnification
The number of times larger an image appears, compared with the size of the object.
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Resolution
The clarity of an image; the higher the resolution, the clearer the image.
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Optical microscopes
Optical (light) microscopes are relatively cheap, easy to use, portable and able to study whole living specimens. They allow magnification up to x1500 or x2000, however, the resolution is limited. They use visible light wavelength between 400 nm.
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Calculating magnification
Total magnification = Magnifying power of the objective lens x Magnifying power of the eyepiece lense
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Photomicrograph
Photograph of an image seen using an optical microscope.
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Laser scanning miscroscopes
Use laser light to scan an object point by point and assemble, by computer, the pixel information into one image, displayed on a computer screen.
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Electron microscopes
Uses a beam of electrons wavelength about 0.004 nm, giving an image with greater resolution. Electrons are fired from a cathode and focused by magnets onto a screen/photographic plate. They are large, expensive and need skill and training to use.
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Transmission electron microscopes
A specimen is chemically fixed by being dehydrated and stained with metal salts; only some of the beam of electrons passes through, forming a 2D grey-scale electron micrograph.
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Scanning electron microscope
A specimen is coated with a fine film of metal which causes secondary electrons to 'bounce off' it, allowing the specimen's surface to be focused onto a screen, producing a 3D electron micrograph with a magnification from x15 up to x200000.
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Other cards in this set

Card 2

Front

The clarity of an image; the higher the resolution, the clearer the image.

Back

Resolution

Card 3

Front

Optical (light) microscopes are relatively cheap, easy to use, portable and able to study whole living specimens. They allow magnification up to x1500 or x2000, however, the resolution is limited. They use visible light wavelength between 400 nm.

Back

Preview of the back of card 3

Card 4

Front

Total magnification = Magnifying power of the objective lens x Magnifying power of the eyepiece lense

Back

Preview of the back of card 4

Card 5

Front

Photograph of an image seen using an optical microscope.

Back

Preview of the back of card 5
View more cards

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