Alternating Current

Mean and RMS Value of AC

The root mean square (RMS) value represents the effective or DC equivalent of an alternating current, defined as the square root of the mean of squared instantaneous values over a complete cycle.

AC Circuit with L, C, and R

Studies how individual components respond to AC: resistors are in phase, inductors cause voltage to lead current by 90 degrees, and capacitors cause current to lead voltage by 90 degrees.

Phasor Diagrams and Impedance

A graphical method using rotating vectors (phasors) to represent alternating voltages and currents, combining resistance and reactance into a single opposition called impedance (Z).

Series LCR Circuit and Resonance

When inductive reactance equals capacitive reactance, the circuit achieves resonance, resulting in maximum current and minimum impedance, acting as a natural frequency filter.

Power in AC Circuits

Real power consumption depends not just on voltage and current, but also on the power factor (cos phi), meaning pure inductors and capacitors consume zero average power.

Transformers

Devices based on mutual induction that step up or step down alternating voltages with high efficiency, forming the backbone of long-distance power transmission.