hi hero,Yes, I've read and understood that but I've learned nothing new. It doesn't mean that Ohm's law doesn't apply at all V still equals IR, it's just that the resistance of a non-linear element just changes as a function of voltage or current as I explained a few posts ago.

http://www.electro-tech-online.com/threads/ohms-law.106871/#post875134

The part of the Wiki article discussimg Johnson–Nyquist noise doen't debunk Ohm's law any more than the random movement of particles in a liquid or gas above absolute zero violates the first and second laws of thermodynamics.

I am not trying debunk Ohms law, but the formula V= I * R is not Ohms Law.

Ohms Law defines the current flowing in a conductor is directly proportional to the applied voltage and inversely proportional to the conductors resistance.

You seem to have disregarded this section of the text:

The point you are making regarding non ohmic is also valid, provided that the measurements are made over a short 'linear' section of say a diode curve.In a true ohmic device, the same value of resistance will be calculated from R = V/I regardless of the value of the applied voltage V.That is, the ratio of V/I is constant, and when current is plotted as a function of voltage the curve is. The operator "delta" (Δ} is used to represent a difference in a quantity, so we can write ΔV = V1-V2 and ΔI = I1-I2. Summarizing, for any truly ohmic device having resistance R, V/I = ΔV/ΔI = R for any applied voltage or current or for the difference between any set of applied voltages or currents.linear(a straight line). If voltage is forced to some value V, then that voltage V divided by measured current I will equal R. Or if the current is forced to some value I, then the measured voltage V divided by that current I is also R. Since the plot of I versus V is a straight line, then it is also true that for any set of two different voltages V1 and V2 applied across a given device of resistance R, producing currents I1 = V1/R and I2 = V2/R, that the ratio (V1-V2)/(I1-I2) is also a constant equal to R

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