Re: Paul's message about Ampere and Bio.

[Ludwik Kowalski <kowalskiL@MAIL.MONTCLAIR.EDU>]

Paul asked:

> Hi all. is B=mu noughttimes current/2pi r not biot-savarts
> law. One of my parents friends, a physics teacher, says it
> is ampere's law. Who is correct?

I suspect that Ampere was not familiar with the concept
of B, as we define it today. The concept of "lines of force"
(able to act on a magnetic pole), invented by Faraday, did
not become popular before it was publicized by Maxwell.
Is this correct? If so then neither Bio nor Ampere were
authors of our formulas with B. These formulas were
named after the scientists to honor initial contributions,
not to assign authorship. There were certainly no mu_o
in the original expressions.

Bio and Savart did show (experimentally) that the
magnetic force (per unit pole, if you wish) is directly
proportional to the current in a long wire and inversely
proportional to the distance from the wire. That is all.
The concept of "current element" was invented by
Ampere. But I do not think that Ampere was the author
of what most US textbooks call the Bio-Savart Law.
 From what I recall Ampere was calculating forces
between wires with currents directly, not by using
the intermediate concept of B. But I have no access to
his papers. Can somebody check this for us?
Ludwik Kowalski