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Re: Ohm's Law



How about:
Resistance is the ratio of voltage to current, which remains reasonably
constant for many materials at a given temperature, though for some the
ratio falls (metals) or rises (carbon etc) with temperature. Other
materials have a ratio that varies depending on the voltage, and others
have a ratio that depends on the applied current at a constant temperature.

Brian W



At 08:41 AM 2/8/02, you wrote:
I take "Ohm's Law" to be that the resistance is independent of the voltage.
Is this wrong?

____________________________________________
Robert Cohen; rcohen@po-box.esu.edu; http://www.esu.edu/~bbq
Physics, East Stroudsburg Univ, E. Stroudsburg, PA 18301

> -----Original Message-----
> From: Bob Sciamanda [mailto:trebor@VELOCITY.NET]
> Sent: Thursday, February 07, 2002 8:09 PM
> To: PHYS-L@lists.nau.edu
> Subject: Re: Circuit Question
>
>
> Tina,
> I know others have a different view, but I take "Ohm's law"
> as simply a
> definition of resistance - it defines a useful property of
> matter in many
> common DC circuit circumstances. I think this is the simplest way to
> present it. The definition tells us how to measure the
> resistance of a
> "resistor". Then a problem can specify the EMFs and the relevant
> resistances in a circuit, so that the student can calculate
> currents and
> potential differences. Don't weaken. Learn by teaching and asking.
>
> Bob Sciamanda (W3NLV)
> Physics, Edinboro Univ of PA (em)
> trebor@velocity.net
> www.velocity.net/~trebor
> ----- Original Message -----
> From: "Tina Fanetti" <fanettt@QUEST.WITCC.CC.IA.US>
> To: <PHYS-L@lists.nau.edu>
> Sent: Thursday, February 07, 2002 6:29 PM
> Subject: Re: Circuit Question
>
>
> > Thank you to all who answered.
> >
> > However, is it really vaild to answer a question about a
> concept by saying
> look at this or that law.
> >
> > I mean really. I can solve for Ohm's law in a variety of
> situations. ANd
> I can look at Ohm's law and know if I have a circuit this and
> that is going
> to happen.
> >
> > Now I have a masters degree. I am teaching people who can
> barely solve
> algebraic problems.
> >
> > If I told them to look at Ohm's law and think real hard
> about it they
> would revolt. The students would not get it and quit.
> >
> > Yes I can say look at Ohm's law and show them via Ohm's law but that
> doesn't help us.
> >
> > I am now afraid to ask any more questions on this list for
> fear they are
> too "simple" for the people on this list.
> > It seems like this list is geared more towards topics at
> the advanced
> level and grad level and not to the intro topics that most must teach.
> >
> > Tina
>

Brian Whatcott
Altus OK Eureka!