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- Path: sparky!uunet!elroy.jpl.nasa.gov!usc!rpi!newsserver.pixel.kodak.com!psinntp!psinntp!kepler1!andrew
- From: andrew@rentec.com (Andrew Mullhaupt)
- Newsgroups: sci.physics
- Subject: Re: Lightning
- Message-ID: <1098@kepler1.rentec.com>
- Date: 21 Jul 92 02:41:02 GMT
- References: <1992Jul18.082030.6453@cco.caltech.edu> <1085@kepler1.rentec.com> <9870@sun13.scri.fsu.edu>
- Organization: Renaissance Technologies Corp., Setauket, NY.
- Lines: 19
-
- In article <9870@sun13.scri.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr) writes:
- >In article <1085@kepler1.rentec.com> andrew@rentec.com (Andrew Mullhaupt) writes:
- >>
- >>You hear lightning on AM radio so it isn't just DC, right? It's pretty broad
- >>band, since you can get it all over the spectrum. So it's perhaps true that
- >>initially the spark crosses the gap in some directional sense, there's a lot
- >>of AC in a lightning strike.
-
- >Remember, you do not need an AC current to generate an E-M wave, just a
- >time-varying current. A DC current pulse will do just fine. In fact,
- >something of that sort is necessary to get the broad frequency range.
-
- A DC current pulse has AC in it. (In some sense it doesn't mean much to
- talk about pure AC or DC in this kind of situation.) The situation is
- a lot like a spark across air in the lab. In these, (remember Hertz
- and Marconi), there is known to be lots of AC.
-
- Later,
- Andrew Mullhaupt
-