In an AC circuit, what is the phase difference across an ideal resistor?

In an AC circuit, the phase difference across an ideal resistor is zero degrees. This means that the voltage across the resistor and the current through the resistor are in perfect synchronization. They reach their maximum values at the same time and cross through zero together. This is because an ideal resistor obeys Ohm's law, which states that the current through a resistor is directly proportional to the voltage across it, with no time delay or phase shift.

In practical terms, this means that there is no reactive component (like that found in inductors or capacitors) that would cause the current and voltage to be out of phase with each other. Thus, the relationship remains purely resistive, leading to a phase difference of zero degrees. Understanding this concept is essential for analyzing more complex AC circuit behavior where elements like capacitors and inductors are present, as they introduce phase differences that can complicate the analysis.