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Phasors
Intermediate
Rotating vectors represent AC quantities.
Rotating vectors represent AC quantities; their lengths are amplitudes and angles are phases. Adding phasors gives total voltages.
Voltages across R, L, C add as vectors at 0°, +90°, −90°.
Phasors only apply for the same frequency.
In more detail
A phasor is a rotating vector that represents a sinusoidal quantity, with length equal to amplitude and angle equal to phase. Phasors turn differential equations of AC circuits into algebra.
Real-world uses
- Engineers analyse AC circuits and filters using phasor diagrams.
- Power engineers use phasors to study grid operation.
- Engineers analysing AC circuits use phasor diagrams to add voltages and currents with different phases quickly.
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Frequently asked questions
Are phasors real vectors?
They are mathematical tools, and the real physical quantity is the projection onto an axis.
Do I need complex numbers?
They make phasor calculations much simpler.
Why use phasors instead of sine functions?
Adding phasors is simpler than adding sinusoids, and it gives the amplitude and phase directly.
Related topics in AC Circuits & EM Waves
Alternating current · Peak and RMS values · Average power in AC · Resistor in AC · Inductor in AC · Capacitor in AC