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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.
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 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. 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.