# Ohm's Law or not Ohm's Law... That is the question

Discussion in 'General Electronics Discussion' started by CDRIVE, Sep 19, 2012.

1. ### CocaCola

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Apr 7, 2012
If you bothered to actually read the thread the argument revolves around the definition of what Ohm's Law is defined as, not necessarily it's application and formulating an answer that can be applied to it...

Is it simply...

I = V ÷ R

or

When you don't have a true resistance are you allowed to estimate and/or derive at a theoretical resistance by the use of additional equations or whatever, and still call it Ohm's Law?

2. ### CDRIVEHauling 10' pipe on a Trek Shift3

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May 8, 2012
After Bob's last post I did a search "AC Ohms Law Origins". I was hoping to attribute a name in connection with Z concepts. According to Wiki, It seems to fall under Maxwell's Equations.

For Inductors and Capacitors, they are but 90° out of phase.

As for the other components listed In there you have to factor in the context in which I made that statement. If you recall I was working with a young fellow building a 12AU7 amplifier. Note that I said "governed", not "obey".

That statement was made in the following context:

An Instructor draws a BJT (Q1) amplifier on the black board. It includes an Emitter Resistor (Re), Collector Resistor (Rc), Base to GND Resistor (Rbg) and a Base to Vcc Resistor (RbVcc). The instructor gives the class the value of only one Resistor, the Emitter Resistor (Re) = 100R. The Instructor then writes the following on the board Vcc = 12V, Q1(hFE) = 100, Ic = 5mA, Vc = 6V. Solve for the values of Rc, Rbg, RbVcc. I_Rbg = 10 x Ib.

These students will most definitely utilize their new found skills with Ohms Law to solve this class work. In the end the behavior of Q1 is most definitely governed by Ohms Law.

There may exist a component that I can't spin into an Ohms Law scenario like this but, off hand, I can't think of one.

Chris

Last edited: Sep 29, 2012