Electromagnetic waves - Harvard University

Chapter 8 Electromagnetic wavesDavid Morin, waves we ve dealt with so far in this book have been fairly easy to visualize. Wavesinvolving springs/masses, strings, and air molecules are things we can apply our intuition we ll now switch gears and talk about Electromagnetic waves . These are harder to geta handle on, for a number of reasons. First, the things that are oscillating are electric andmagnetic fields, which are much harder to see (which is an ironic statement, considering thatwe see with light, which is an Electromagnetic wave). Second, the fields can have componentsin various directions, and there can be relative phases between these components (this willbe important when we discuss polarization). And third, unlike all the other waves we vedealt with, Electromagnetic waves don t need a medium to propagate in. They work justfine in vacuum. In the late 1800 s, it was generally assumed that Electromagnetic wavesrequired a medium, and this hypothesized medium was called the ether.

wave equation. In Section 8.3 we see how Maxwell’s equations constrain the form of the waves. There is more information contained in Maxwell’s equations than there is in the wave equation. In Section 8.4 we talk about the energy contained in an electromagnetic wave, and in particular the energy °ow which is described by the Poynting vetor ...

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  Equations, Waves, Electromagnetic, Wave equation, Electromagnetic waves

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