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: Biot, Bio



Referring to this:

Perhaps somebody who knows will comment.

JohnD wrote:

Or perhaps you could find out for yourself.

There are a number of well-known widely-available sources.
-- What do they say?
-- If what they say is in doubt, please explain why.

I was expressing a suspicion that what we call the Biot-Savart
formula today was formulated by Ampere rather than Biot.

I did consult one source today to refresh my memory.
According to the multi-volume "Dictionary of Scientific
Biography" the experimental discovery that the magnetic
force [on a pole of a long compass needle] is proportional
to I/r was "Biot's miscellaneous contribution". The discovery
of Biot and Savart (where I is the current and r is distance)
was announced on October 30, 1820, shortly after the
Oersted's discovery.

The biography of Ampere, on the other hand, indicates that
the fundamental concept of "current element" was invented
by him. He used it extensively to calculate forces between
electric currents in wires. A brief description of Ampere's
work suggested to me that he is more likely to be the author
of the B&S law than Biot. (The current element, i*dl, is the
essential theoretical component if the B&S law.) I suspect
that Biot and Savart discovered the 1/r relation (for a long
wire) while Ampere showed that this relation, and many
more, can be derived from something "more basic," from
the 1/r^2 law.

But I am not a historian who read original papers. That is
why I asked for comments of those who know better.
Ludwik Kowalski