Although Ohm´s Law in the original form is applied to DC circuits, it applies to AC as well, as long as the resistance is considered pure. Ohm´s Law for AC circuits is often written with Z replacing R as given in the next formula:
Formula 1
Vrms = Z x Irms
Where:
Vrms is the rms voltage accross the circuit in volts (V)
Z is the impedance in ohm (Ω)
Irms is the rms current through the circuit in amperes (A)
Derivated Formulas:
Formula 2
Irms = Vrms / Z
Formula 3
Z = Vrms / Irms
Application Example:
Calculate the current flowing In a circuit with in impedance of 100 Ω when connected to a 122 Vrms circuit.
Data:
Vrms = 127 V
Z = 100 Ω
Using formula 1:
Irms = 127/100 = 1,27 A
