Circular Magnetisation within Iron Wire

[Danny]

I came across this interesting introduction of a paper from the late 1800's.
A paper by Auerbach.

The Passage of the Galvanic Current through Iron.

When a circuit
consisting partly of a straight iron wire, and containing a battery, is
closed, the current is at first smaller than the normal current, through
what is termed an " extra current," in opposition to the main current.
On opening the circuit on the other hand, the current is greater than
the normal, the " extra current '' being in the same direction with
the main current.

I assume a coil of iron wire is being used because of their being an open circuit current.

The term 'extra current' is certainly of interest for kick generation.

It is interesting that the collapse current is larger than expected.
Perhaps SM used this to advantage in the oscillations between different coils.

The introductions ends by saying:
"Other phenomena connected with the resistance of iron were also
observed, and are discussed at length in the paper."


I would very much like to get a copy of this paper.
If anyone can please post or pm me.

SM made a point of saying the device was made from baling wire - iron wire.
Is this the reason why ?
Any comment on whether this has relevance to SM TPU ?

The introduction can be found on page 2 of this pdf.
http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=CA8793600685&JournalCode=CA

[AhuraMazda]

The paper can be found here but you need access:
http://jphystap.journaldephysique.org/index.php?option=toc&url=/articles/jphystap/abs/1879/01/contents/contents.html&lang=en

[Danny]

Thanks for the link.
Unfortunately the link is for a review of the Auerbach paper by G. FOUSSEREAU and not the actual paper.

[AhuraMazda]

I will try again

[magnetoelastic]

The mechanism here has to do with the change in magnetic flux in the wire as current is applied.  This circular magnetic flux will induce a current at the surface of the wire in the opposite direction to the applied current.

I first noticed this phenomenon a number of years ago.

If you take a heavy iron bar, and momentarily connect it to a high-current source (like a car battery), the outside of the bar will remain cool to the touch for some moments after the current is interrupted.  Within a couple seconds after current is removed, (depending on the diameter of the rod) the outside will gradually become so hot that it can no longer be held.  This is because the induced surface current opposes the applied current, effectively forcing all the current to the center of the bar, heating up only the inside.  It takes some time for this heat to be conducted to the outside of the bar.

M