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To describe light, I need to introduce a few concepts. Please take it as fact that any charged object creates around itself an electric field. This field allows the charge to act with a force on other charges that happened to be nearby. Similarly for magnets. Any magnet (or a wire through which a current is running) creates a magnetic field around itself, and this magnetic field allows the magnet to exert a magnetic force on other magnets or wires through which a current is running. Sometimes, under certain circumstances, these electric and magnetic fields travel through space in socalled electromagnetic waves. They do not need a carrier, as waves in a lake need water or sound needs air. They just travel through space from sources to receivers. As their name suggests, they all have two components: E(r,t), the electric component, and B(r,t), the magnetic component. The propagation of these components is described by the wave equations shown above. That is a system of partial differential equations. With mathematical tricks, one can solve these equations, and obtain various interesting solutions. Please go to the next page to find out how to create EM waves and to see some simple solutions of the wave equations. 

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last modified 1/5/2001 email Fermilab 