Saturday, July 9, 2011

Class IX, BIOLOGY, "Electron Microscope"

Electron Microscope

This is the most advanced form of microscope. Its resolving power is 250 times or more that of a compound microscope. In this microscope, a beam of electrons under high voltage is passed through the object and its image is reflected on to a screen through an electro magnetic lens to make a photograph.
With the help of microscope, any object an be magnified up to 250,000 its original size.

Comparison of Light Microscope and Electron Microscope

Light Microscope
The radiation source is light so it is called light microscope.
Wavelength of light is 400 – 700 nm.
Maximum resolution is 200 nm.
Maximum useful magnification is X 1500 with eye.
Lenses are used.

Electron Microscope

The radiation source is beam of electrons, so it is called Electron Microscope.
Wavelength of beam of electrons is 0.005 nm.
Maximum resolution is 0.5 nm.
Maximum useful magnification is X. 250,000 on screen as image or photograph.
Electromagnets are used.

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