Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Bar magnets, was magnetic circuits



In a message dated 2/19/01 2:44:33 AM Eastern Standard Time, jsd@MONMOUTH.COM
writes:

<< I think scaling laws are very important. The field of a point charge
scales like 1/r^2. The field of a line charge scales like 1/r. The field
of a surface charge scales like r^0.

Saying that there is some magical "1/r^2 law" that applies to everything is
just not right. Certainly there is no 1/gap^2 law that applies to
parallel-plate capacitors. Why should there be a 1/gap^2 law that
magically applies to the magnetic "charges" (poles) on the ends of bar
magnets?
>>
This is not directly related to the affects of magnetic forces but the same
scaling laws you site are also relevant to the calculation of radiation
levels which result from some formation of radioactive materials and an
attempt is made to calculate the radiation field strength at some given
distance from the source. ( Assuming zero attenuation) However the reason I
post this is that it seems clear that the distance each of the different
scaling laws are apply is determined by the geometry of the source. Could
anyone on this list provide an explanation as to how one would go about
calculating the distances where the various scale laws apply as a function of
the geometry of the source? Of course this would apply to electrostatic,
magnetic and even light propagation as well as other radiation fields.

Bob Zannelli