Talk:Ohm's law
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The page says "Ohm's law (named after Georg Ohm, who discovered it) states that when the resistance of a device is independent of the voltage applied across it, and therefore of the current through it as well."
What is that "when" doing there? Can it come out? Vicki Rosenzweig, Saturday, June 22, 2002
UNIXCOFFEE928Hi! Can someone state the history of the variable 'I' in the context of Ohm's law? What was currrent originally called, for it to be labeled as 'I'?
```Nevermind, I found it, I'll add it.
There are more constraints to Ohms law. 1. The voltage/current/resistance has to be constant - as ohm defined. This law will be challenged if any of them fluctuates. 2. This is for conductors - not insulators or semi-conductors or super conductors.
explanation of present ohm's law
Could someone explain how Ohm's law went from J=pE to V=IR?
- its<math>\mathbf{j} = \sigma \cdot \mathbf{E}<math> not <math>\mathbf{j} = \rho \cdot \mathbf{E}<math>
- basically <math>\sigma=\frac{1}{\rho}<math>
- <math> \rho=\frac{RA}{L} <math>
- <math>\mathbf{E}=\frac{V}{L}<math>
- <math>\mathbf{j}=\frac{I}{A}<math>
- then just substiture into <math>\mathbf{j} = \sigma \cdot \mathbf{E}<math> cancel and rearrange.