RC Series Circuit:

An RC series circuit consists of a resistor and a capacitor connected in series to a voltage source. The capacitor is an energy storage device that stores electric charge. When a voltage is applied to the circuit, the capacitor charges up to the same voltage as the source.

Phasor Diagram:

To understand the relationship between voltage and current in an RC series circuit, we use phasor diagrams. Phasor diagrams are graphical representations of the magnitude and phase of AC voltages and currents.

Phase Relationship:

In an RC series circuit, the applied voltage leads the capacitor voltage. This means that the voltage across the resistor is in phase with the current, but the voltage across the capacitor lags the current.

Explanation:

When an AC voltage is applied to the circuit, the voltage across the resistor and capacitor vary sinusoidally with time. However, the voltage across the capacitor is delayed with respect to the applied voltage. This is because the capacitor stores energy in the form of electric charge, and takes time to charge and discharge.

The phase angle between the applied voltage and the capacitor voltage is given by:

θ = tan⁻¹(1/ωRC)

where θ is the phase angle, ω is the angular frequency of the applied voltage, R is the resistance of the circuit, and C is the capacitance of the capacitor.

When the frequency of the applied voltage is low, the phase angle between the applied voltage and the capacitor voltage is large. This means that the voltage across the capacitor lags the applied voltage by a large amount.

When the frequency of the applied voltage is high, the phase angle between the applied voltage and the capacitor voltage is small. This means that the voltage across the capacitor lags the applied voltage by a small amount.

Conclusion:

In an RC series circuit, the applied voltage leads the capacitor voltage. The voltage across the resistor is in phase with the current, but the voltage across the capacitor lags the current. This phase relationship is due to the energy storage properties of the capacitor.