Actually, Hp made a Rb vapor magnetometer in the '60s. We had one attempted to measure the total electric charge moved by lightning strokes. A sensitive compass can be used too... Don
Bruce Griffiths > Bob Camp wrote: >> Hi >> >> I finally found a number listed for the external magnetic field >> sensitivity of a fairly small Efratom rubidium. It's specified as 3 >> x10^-11 per 0.1 mili tesla. I did *not* make up those units, that's the >> way they stated it. If that's correct *and* my very rusty physics is >> also right: >> >> A 1 A change in a wire one inch away will produce 0.08 mili tesla of >> field change. That should produce 2.36x10^-11 frequency change. >> Obviously it's not quite that simple since the wire is a lot closer to >> the device than the device is large. I suppose a more proper measure >> would be 1" away from the physics package. Even then the field is not >> uniform over the entire physics package. >> >> The reasonable conclusion would seem be that amp or multi amp conductors >> at an inch or more from the package might indeed be an issue at the >> 1x10^-11 level. At the very least twisted paris for DC in the area sound >> like a good idea as opposed to random wire routing. It also sounds like >> a good idea to simply not have that sort of current running right by the >> physics package. >> >> Ok, what did I miss that time. Hand calculating DC fields is something I >> haven't done in ... ummm,... errr ... let's leave it at "quite a while". >> >> Bob >> _______________________________________________ >> > Yes, its about 80uT at 1" radial distance from an infinite length of > straight conductor carrying 1A. > B~ 2E-7(I/r) > > Smaller for finite wire lengths (but in this case one has to consider > the geometry of the other conductors forming the loop). > > Since the earths field lies in the 30uT to 60uT range, one may be able > to use the Rubidium standard as an insensitive compass. > > Bruce > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
