Why is Ohms Law important?

Answer 1

The simple answer is that it isn't! Ohm's Law applies to so few conductors and electrical devices that it hardly qualifies as a 'law' at all. For Ohm's Law to apply, the ratio of the voltage across a conductor (or any sort of load) to the current through that conductor must be constant for variations in voltage, and this occurs in very few conductors.

Many people, who should know better, mistakenly believe that the equation, R = V/I, represents Ohm's Law. This is incorrect, as the equation is derived from the definition of the ohm (being defined as a 'volt per ampere'), and not from Ohm's Law. This equation is universal, and applies in situations where Ohm's Law doesn't. For example, the ratio of voltage to current for a tungsten lamp changes as the voltage across the filament changes and, so, tungsten doesn't obey Ohm's Law. However, for any particular voltage, the resistance of tungsten AT THAT VOLTAGE can be determined by the equation.

Many scientists and engineers believe that Ohm's Law should be a law at all. A well-known MIT professor, for example, goes as far as to say that "Ohm's Law is a fake"! In my opinion, there doesn't seem to be any good argument for teaching Ohm's Law beyond its historical significance.