Ohm's law

In chemistry, that compound is Boron, Uranium, Nitrogen, and Potassium.

Then how did they define R? Isn't Ohm's law just the definition of R?

On Fri, 20 Nov 2015 03:01:04 -0500, "Tom Del Rosso" Gave us:

Ohm defined what it had to be. 1 amp was a known. 1 volt was a known.

So the formula has to be what the formula is. It is what it is. He simply quantified it based on other aspects of the electrical realm, which were already in place.

That's what I mean by 'Ohm's law defines R'.

So my question is how could they use 'R' before Ohm.

On Fri, 20 Nov 2015 06:30:10 -0500, "Tom Del Rosso" Gave us:

Did they? Did they even consider the concept of more or less 'resistance' to flow in a circuit or resistive elements?

When did Kirchoff hit the scene?

Read Tim's post that I quoted.

Ohm observed that current is proportional to the voltage across a conductor. That is his "law." Later, the proportionality unit was named for him. There was no R before Ohm, because the effect was not known.

Hi Tom, I don't think they had defined resistance yet. They were just looking at the relation between current and voltage... They didn't know if that was linear or not. Ohm was using thermopiles as voltage sources, ughh.

George H.

Nope. Ohm's law is a material property, not a definition. Diode circuits have volts and amps too, and they do have a very small ohmic (V=IR) range around zero bias. In a diode the nonlinear terms are large enough to dominate above about +-25 mV of bias, whereas in a metal the resistance at constant temperature hardly changes at all.

Cheers

Phil Hobbs

I just read the article on Barlow's law. Now I see that it wasn't stated as Tim stated it. It just referred to proportion with no units, and in terms of length and cross section.