WaveWatcher:
What's an "LEM" pulse?
This is the best explanation, I've seen posted, of the most common example: http://www.montalk.net/notes/longitudinal-waves. >>Edit: I don't agree with all of his ideas. One detail about LEM I find untrue is "Notice also that there is no vorticity in this field, and therefore no magnetic field". Rather, there is vorticity and that rotation appears in the travel of charge motion and a magnetic spin-wave. This vorticity only exists with such a wave that is not from a point-source, such as a sphere. Any LEM that is directional or multi-directional (not from a point-source) will have rotation in the electric and magnetic potential. Any LEM from a point-source is not LEM but simple radiation of charge potential. (I believe any magnetic from a point-source is self-cancelling.) I think most will agree a spin-wave or circular polarization (as simple and common as circular polarization is) is denied to exist or beyond many experimenter's capabilities to detect. >>End Edit For more in-depth info you could purchase the complete text of the pictured document. I find it more fun to build ways to produce them. If your scope is faster than most scopes owned by a home experimenter you may see an LEM pulse as a single vertical line. Displaying any more characteristics is difficult and requires the understanding that not all scope traces are obtained by making an electric-only connection to points where things of interest aren't happening. i.e. the active instead of passive device.
« Last Edit: 2010-05-15, 14:37:53 by WaveWatcher »
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