Phasor diagrams

Definition

Phasor diagrams are graphical representations of the magnitudes and phase relationships between sinusoidal functions in AC circuits. They simplify the analysis of alternating currents and voltages by converting complex numbers into rotating vectors.

5 Must Know Facts For Your Next Test

1. Phasor diagrams represent sinusoidal waveforms as vectors in a complex plane, with their lengths corresponding to amplitudes and angles representing phase differences.
2. The horizontal axis of a phasor diagram typically represents the real part (cosine component) of the waveform, while the vertical axis represents the imaginary part (sine component).
3. Phasors rotate counterclockwise at an angular velocity equal to the angular frequency of the AC signal.
4. Using phasor diagrams can simplify calculations involving AC circuits, particularly when dealing with series and parallel combinations of impedances.
5. Impedance in an AC circuit can be represented as a phasor combining resistance (real part) and reactance (imaginary part), making it easier to analyze voltage and current relationships.

Review Questions

• What does a phasor diagram represent in an AC circuit?
• How does a phasor diagram help in simplifying AC circuit analysis?
• In what direction do phasors rotate on a phasor diagram, and what determines their angular velocity?

Related terms

Impedance: A measure of opposition to alternating current, comprising both resistance (real part) and reactance (imaginary part). Represented as $Z = R + jX$.

Reactance: The imaginary component of impedance that represents opposition due to inductors or capacitors. It varies with frequency.

Phase Angle: The angle difference between two sinusoidal waveforms, often measured in degrees or radians. Represents how much one waveform leads or lags behind another.