Re: [rete] Models (fwd)

[Bernard Cleyet <anngeorg@PACBELL.NET>]

sl. off the topic:

I've found it interesting that early (<30's?) electricity texts used
mechanical analogies to teach electricity, e.g., dash pots for
resistors, flywheels, etc.  Now it's the reverse!

Until about 20 years ago analog computers were faster than digital for
modeling the above using op. amps. etc.  I still prefer them as they are
more "transparent" (less black boxy).   However, recently I've used a
modeler that uses icons that imitates the analog computers we once used
at UCSC.  So another technology consigned to Physics museums.

bc

Joseph Bellina wrote:

> I know that in the past there have been conversations about models we use,
> in particular the fluid model for electric current.  I thought some of you
> might find this interesting.
>
> cheers,
>
> joe
>
> Joseph J. Bellina, Jr.               574-284-4662
> Associate Professor of Physics
> Saint Mary's College
> Notre Dame, IN 46556
>
> ---------- Forwarded message ----------
> Date: Mon, 08 Sep 2003 13:48:02 +0100
> From: Roland Wittje <roland.wittje@phys.ntnu.no>
> Reply-To: rete@maillist.ox.ac.uk
> To: rete@maillist.ox.ac.uk
> Subject: Re: [rete] Models
>
> Dear Retians, dear Paolo,
>
> I had posted this reply to Paolos request about ten days ago. It seems
> like it has never been distributed, so I am trying again:
>
> Apart from Bjerknes' hydromechanical analogies of electricity and
> magnetism, which I had demonstrated on the Scientific Instrument Symposium
> in Stockholm in 2001, I also have a simple hydromechanical model of a
> Wheatstone bridge in my collection. The model consists of a tin sheet
> container and a system of channels made of lead, for the fluid, most
> probably whater, to run into a tin trunk. The model was most probably made
> locally at the instrument workshop of the physics department of the
> Norwegian Institute of Technology, Trondheim, between 1910 and 1915. I
> have put up a photo of it being set up for lecture demonstrations in 1915
> on my internet page:
>
> http://www.phys.ntnu.no/~rolandw/wheatstone.jpg
>
> The model is still in the collection, but partly damaged.
>
> Several of the instruments of Carl Anton Bjerknes' research program on the
> hydromechanical analogies of electricity and magnetism are preserved at
> the Norwegian Museum of Science and Industry in Oslo. I also found pieces
> of the instrument bought by Philip Lenard in 1909 on an attic of the
> University of Heidelberg.
>
> I hope that more of these mechanical and hydromechanical models of
> electricity and magnetism have survived, adding streamline models and
> hydromechanical models of to-phase and three-phase electric motors to the
> list of devices that existed.
>
> Best wishes
>
> Roland
>
> -------------------------------------------
>
> Roland Wittje
> Dep. of Physics
> NTNU
> 7491 Trondheim
> Norway
>
> Tel. +47-73-593356
> Fax +47-73-597710
> E-mail: Rolandw@phys.ntnu.no
>
> On Mon, 18 Aug 2003, Paolo Brenni wrote:
>
> > Dear Retians,
> > if you are not still on vacation I have a question for you....
> > I am looking for surviving mechanical or hydraulic models used for
> > illustrating electrical phenomena, theories as well as the working of
> > electrical apparatus (Wheatstone bridge, Leyden jar, etc).
> > Of couse I know of the famous Maxwell's, mechanical model of electrical
> > induction, but do the models of Lodge or Fitzgerald survives?
> > Thanks
> > Yours Paolo Brenni
> >
> >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: rete-unsubscribe@maillist.ox.ac.uk
> > For additional commands, e-mail: rete-help@maillist.ox.ac.uk
> >
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: rete-unsubscribe@maillist.ox.ac.uk
> For additional commands, e-mail: rete-help@maillist.ox.ac.uk