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Electron and Gravitational Lenses
Member rating: No Rating | Words: | Submitted: Sat Aug 30 2003
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Electron and Gravitational Lenses The electron microscope uses special lenses to focus a beam of electrons rather than light. Two types of electron lenses are used in electron microscopes: electrostatic and electromagnetic. They create electric and electromagnetic fields to both concentrate and move the beam of electrons. The magnification in magnetic electron microscopes is determined by the strength of the current passing through the electric and electromagnetic lens coils. The image is focused by changing the current through the objective lens coil. Massive objects in the universe can act as lenses by bending the path of light that passes near them. If a light source is behind a massive galaxy, as seen from Earth, deflected light may reach the Earth by more than one path. Operating like a giant gravitational lens that focuses light along different paths, the gravity of the galaxy may make a single light source appear...
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