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Creating an electromagnetic wave

Creating an electromagnetic wave - Those two points are key...

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Creating an electromagnetic wave We've already learned how moving charges (currents) produce magnetic fields. A constant current produces a constant magnetic field, while a changing current produces a changing field. We can go the other way, and use a magnetic field to produce a current, as long as the magnetic field is changing. This is what induced emf is all about. A steadily-changing magnetic field can induce a constant voltage, while an oscillating magnetic field can induce an oscillating voltage. Focus on these two facts: 1. an oscillating electric field generates an oscillating magnetic field 2. an oscillating magnetic field generates an oscillating electric field
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Unformatted text preview: Those two points are key to understanding electromagnetic waves. An electromagnetic wave (such as a radio wave) propagates outwards from the source (an antenna, perhaps) at the speed of light. What this means in practice is that the source has created oscillating electric and magnetic fields, perpendicular to each other, that travel away from the source. The E and B fields, along with being perpendicular to each other, are perpendicular to the direction the wave travels, meaning that an electromagnetic wave is a transverse wave. The energy of the wave is stored in the electric and magnetic fields....
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