What georg Simon ohm stated in the ohm's law?

Answer 1

Ohm's law: (In today's context): Voltage = current times resistance

Discussion:

Originally, Ohm's Law stated that 'the current flowing through a conductor at constant temperature is proportional to the potential difference across the ends of that conductor'.

This "proportionality" has evolved into the definition of the ohm, or the resistance.

Sometimes, the law has been quoted as 'for a conductor in a given state, the electromotive force is proportional to the current'.

This accounts for the fact that temperature is a factor is determining resistance. While there is no mention of 'resistance' in the original law, a constant resistance is implied by the requirement for a 'constant temperature'.

In fact, the equation referred to in the "today's context" answer is derived from the definition of the ohm, which is expressed in terms of a volt per ampere -i.e. R = V/I, and not from Ohm's Law.

One thing that can make it easier to understand this supposed controversy, is the point that Ohm's Law (today's version) defines the ohm as the voltage divided by the resistance, but it makes no mention of the fact that no device, conductor, resistor, or otherwise, is truly ohmic, i.e. having constant resistance.

Using this understanding, one can derive the resistance of a diode or even a light bulb, both of which certainly do not have constant resistance. You just measure current and voltage, and calculate resistance, understanding that if current and/or voltage changes, so does resistance, requiring a new calculation.

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