Re: R = V/I ?

["Richard W. Tarara" <rtarara@SAINTMARYS.EDU>]

Another reason to avoid this usage is the confusion it causes the beginning
student.  They may look at R = V/I and say OK, if we increase V then R
increases.  While this might happen (to some extent) with a light bulb, it
is definitely not the behavior we use Ohm's Law to describe.  Again, we have
the problem of just how students interpret equations.  Many will look at
them as definitions rather than functional relationships.  In my mind, the
only time to use R = V/I is in a situation where you know both the voltage
across and current through an object and want to know the resistance.  In
this sense, the relationship gives you a MEASUREMENT of R but not a
definition of R.

Rick

----- Original Message -----
From: "Michael Edmiston" <edmiston@BLUFFTON.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, May 05, 2000 12:09 PM
Subject: R = V/I ?


> Robert Cohen asks why we cannot use V/I as the definition of resistance.
I
> think this is a sufficiently different topic that I will boldly change the
> subject.
>
> I believe many people, and many textbooks, do use this definition.  The
> textbook I am using (Tipler) says this.