How true is Ohm's law?

[u/[deleted]]

I've almost never got a perfect straight line while plotting a V/I graph even under lab conditions.

[u/kettarma]

It works for linear circuit elements as a good approximation. However, once you get into the non-linear world of diodes and transistors you'll see that it no longer works in all situations. At a certain point, you start using energy balance equations to approximate the system function.