🚀 go-pugleaf

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