Write a note on electron microscope.

ELECTRON MICROSCOPE:

Electron microscope was invented in 1935. It has a resolving power 250 times or more than that of. a compound microscope. It uses a beam of electron as a source of illumination. The electron beam increases its resolving power. Modern electron microscope can achieve a resolution of .about 0.2 nm, a thousand times improvement over light microscope. The electron microscope uses electromagnet as lenses instead of glass lenses. Its image cannot be focused in human eye, therefore screen or photographic plates are used to review and focus these images. Electron microscope has a capacity to magnify an object up to 250,000 times of its original size. 

Electron microscopes reveal many organelles that are impossible to resolve with the light microscope.

In electron microscopy, chemical and physical methods are used to prepare samples which not only kill cells but also may introduce artifacts. A light microscope has many advantages especially for the study of live cells.