URGEN PLZ WRITE AT LEAST A THREE SENTANCE LOGICAL SUMMARY FOR THIS PIECE OF TEXT Different types of microscopes have different qualities and uses. Light microscopes that use two lenses are called compound light microscopes. In a typical compound light microscope, a light bulb in the base shines light up through the specimen, which is mounted on a glass slide. Both lenses magnify the image. Thus, a microscope with a 40 X lens and a 10 X lens produces a total magnification of 400 X. The most powerful compound light microscopes have a total magnification of up to 2,000 X, which is sufficient for viewing objects as small as 0.5 μm in diameter.

Electron beams have a much shorter wavelength than that of visible light, so electron microscopes are much more powerful than light microscopes. Electron microscopes can magnify an image up to 200,000 X, and they can be used to study very small structures inside cells or on cell surfaces. In electron microscopes, both the electron beam and the specimen must be placed in a vacuum chamber so that the electrons in the beam will not bounce off gas molecules in the air. Because living cells cannot survive in such a powerful vacuum, they cannot be viewed using electron microscopes. Also, electron microscope images are always in black and white unless scientists have added artificial colors to make certain structures more visible.

Two kinds of electron microscopes are transmission electron microscopes and scanning electron microscopes. In a transmission electron microscope, the electron beam is directed at a very thin slice of a specimen stained with metal ions. A transmission electron microscope (TEM) can reveal a cell’s internal structure in fi ne detail. In a scanning electron microscope, the electron beam is focused on a specimen coated with a very thin layer of metal. A scanning electron micrograph (SEM) shows three-dimensional images of cell surfaces.