On Wednesday 30 January 2008, Douglas A. Tutty wrote: > On Thu, Jan 31, 2008 at 02:11:54AM +0100, ropers wrote: > > On 30/01/2008, Douglas A. Tutty <[EMAIL PROTECTED]> wrote: > > > She's also sensitive to lower-freq and even DC electric fields > > > (e.g. a battery with no external current flow) but in a different > > > manner. > > > > I don't understand what you mean by "DC electric fields" in this > > context. A battery without any current flow is just a container > > with chemicals inside. No electricity, no magnetic field, nothing. > > Sure it does. It has a static electric field since there's a voltage > potential between the two poles. Electricity doesn't just appear > once you put a meter onto a battery; current yes, potential no. > Potential is, well, potential. Also, no batteries are electrically > perfect so they all contain some capacitance that can then interact > if placed in an occilating EMF (IOW, they can act like an antenna). >
Voltage is, by definition, potential difference. You can burry two plates of metal a meter apart from each other and get voltage. When you subject those plates to an increased electro-magnetic field, you get more voltage. http://chem.ch.huji.ac.il/history/bain.html > It all seems strange. Yes, I know the physics of it, but before this > happened, it was something that you paid a lot of money to build a > detector for, for research. > Yes and no. Doing it "right" in a research environment means you'll pay extrodinate amounts of money for accurate and sensitive measurement equipment (as well as a specialized buildng to use the equipment without interference). *BUT* doing it on the cheap is perfectly possible. One of the most fiendishly clever things I've ever seen done was by a "Bring-Up Engineer" (i.e. the guys who debug the initial "bring-up" of newly created circuit board designs) at a poor startup. A very mysterious "something" was causing a component to behave erratically when the power was on but the component tested out perfectly on all of the prototypes. Since there was no way we could afford proper equipment, the guy took a very thin copper wire, wound it around a pencil a few times, separated the coil a bit so it wasn't touching anywhere, then attached a ohm-meter. He ran it over the running board to figure out if the problem was due to significant interference causing the part to malfunction. Sure enough he found it, as well as the source, made a make-shift faraday cage around the source and everything worked. Debugging your wife (if you pardon the analagy) is really not much different; the goal is simply finding and eliminating the sources of the interference. -JCR
