Phase angle

Definition

Phase angle is the measure of the difference in phase between two alternating current (AC) waveforms, typically measured in degrees or radians. It represents how far one waveform leads or lags behind another.

5 Must Know Facts For Your Next Test

1. In an RLC series circuit, the phase angle depends on the relative values of resistance (R), inductance (L), and capacitance (C).
2. The phase angle ($\phi$) can be calculated using $\phi = \arctan((X_L - X_C)/R)$, where $X_L$ is inductive reactance and $X_C$ is capacitive reactance.
3. A positive phase angle indicates that the current lags the voltage, typical in inductive circuits.
4. A negative phase angle means that the current leads the voltage, which occurs in capacitive circuits.
5. When the circuit is at resonance, the phase angle is zero because inductive and capacitive reactances cancel each other out.

Review Questions

• How does an inductive reactance affect the phase angle in an RLC series circuit?
• What equation would you use to determine the phase angle in a series RLC circuit?
• What does a zero-phase angle signify in an AC circuit?

Related terms

Inductive Reactance:

$X_L = \omega L$, where $\omega$ is angular frequency and $L$ is inductance. It causes current to lag behind voltage.

Capacitive Reactance:

$X_C = \frac{1}{\omega C}$, where $\omega$ is angular frequency and $C$ is capacitance. It causes current to lead voltage.

Resonance:

Occurs when inductive reactance equals capacitive reactance ($X_L = X_C$) resulting in a purely resistive impedance and zero-phase angle.