Is VI=P strictly an ohmic relation or does it apply to all types of circuits?
I mean does the object have to follow ohms law V=IR?
I'm not trying to be dense here, but I'm still not quite understanding. Do you mean where "R" is not a complex impedance? Could you please give an example of something that doesn't "follow Ohm's Law"? Thanks.
Something like a light bulb. As the voltage increases, the resistance the lightbulb has isn't linear.
Ah. The resistance of the filimant varies with temperature (this is true of most conductors BTW). It doesn't vary with voltage, per se. A higher voltage causes a larger current to flow, which heats up the filament more, which changes its resistance. V=IR is true at any moment in time, even during the transients like at turn on or if you increase the voltage once the bulb is on.
Do you have another example of what you would consider non-Ohmic?
That was basically it. So I'm guessing that VI=R does work for something like a light bulb right?
For circuits that have reactive devices like inductors and capacitors, the simple linear V=IR Ohm's Law equation is extended to include complex impedances. The equation still works, but "R" --> Z where Z is a complex number.