In an LCR series AC circuit, the current can be in phase with the voltage, lag behind it, or lead it depending on the relative values of the inductance (L), capacitance (C), and resistance (R). The key points are:
- The voltage across the resistor is always in phase with the current.
- The voltage across the inductor leads the current by 90 degrees.
- The voltage across the capacitor lags the current by 90 degrees.
- The total voltage is the vector sum of these voltages.
- If the inductive reactance is greater than the capacitive reactance, the total voltage leads the current (current lags).
- If the capacitive reactance is greater than the inductive reactance, the total voltage lags the current (current leads).
- At resonance, when inductive reactance equals capacitive reactance, the circuit behaves like a pure resistor and the current is in phase with the voltage.
Thus, depending on the L, C, and R values, the current may lead, lag, or be in phase with the applied voltage.