## Verifying ohm's law

How was Ohm's law ever verified?
To verify it you need to measure the current, voltage and resistance over a range of values and show that ohms law satisfies their solution. The catch is that typical ohmmeters do not measure resistance, they measure current and voltage and use ohm's law to find the resistance. If you use an ohmmeter to verify ohms law then you are assuming ohms law is true in order to show that it is true which is logically flawed.
 Recognitions: Gold Member Science Advisor Firstly, Ohm's law isn't a law as such: it is a relation that is approximately applicable in certain situations. That said, if you make sure that a number of conditions are met is should still hold with extremely high accuracy, and it is in fact already used to calibrate the current standards. Resistance, voltage and current form the corners of what is known as the metrological triangle. This triangle has never actually been tested with metrological accuracy (say one part in 10^8), so you are partly correct (albeit not for the reason you mention) The reason is that we don't have a method for realizing the Ampere that is accurate enough. The ohm is realized using the quantum hall effect and the volt using the Josephson effect and these can be measured with very high accuracy. If we had a way of generating a known current that did not depend on neither knowning the voltage nor the resistance(but say a frequency), we could "close" the triangle because we would be able to use two realizations to test the third. Better current sources are becoming available, and the triangle should be closed within a few years,

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 Quote by Shakarri To verify it you need to measure the current, voltage and resistance over a range of values
The essence of Ohm's "law" is that the current through a resistor or other object is proportional to the voltage across it. We basically define R to be the proportionality constant. (Actually it's 1/R if we treat V as the independent variable and I as the dependent variable).

So, simply measure various combinations of V and I, make a graph, and verify that it's linear.

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## Verifying ohm's law

I would argue that Ohm's law is what defines an ideal resistor. There are no ideal resistors in the world, but it's still a useful approximation.
 Recognitions: Gold Member You might find this discussion interesting: http://en.wikipedia.org/wiki/Ohm's_l...scopic_origins

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