Electronic – Does AC phase shift violate Ohms law

circuit analysisinductorresistors

Ok, so I am not new to electronics by any means, but I still can't grasp one key concept: AC voltage-current phase shift. I understand the math behind it, but I need someone to explain to me how it works at the fundamental level.

Let's take into consideration the circuit below.
The input sine voltage is 100V and we know that inductor causes voltage to lag 90 degree behind the current.

  1. My first question is does the phase shift happen in the whole circuit, or only after/before the inductor?

  2. My second question is if we would measure the voltage and current flowing through the resistor R1, and since they are not in phase, doesn't this violate the Ohms law (how can maximum current flow through the resistor when it doesn't experience maximum voltage)?

Thank you.

schematic

simulate this circuit – Schematic created using CircuitLab

Best Answer

The input sine voltage is 100V and we know that inductor causes voltage to lag 90 deg behind the current.

My first question is does the phase shift happen in the whole circuit, or only after/before the inductor?

The current through the entire circuit lags the supply voltage. The voltage across the inductor leads the current.

My second qustion is if we would measure the the voltage and current flowing through the resistor R1, and since they are not in phase, doesn't this violate the ohms law ...

The voltage across the resistor is in phase with the current. The amount by which the current lags the supply voltage is determined by the combined effect of the resistor and the inductor.