Ohm's Law Formulas for D-C Circuits:

Ohm's Law Formulas for A-C Circuits:

In these formulas is the angle of lead or lag between current and voltage and cos = P/EI = power factor.

Resistors in Series: Rtotal = R1 + R2 + R3 + . . . .

Two Resistors in Parallel:

Resistors in Parallel, General Formula:

Sinusoidal Voltages and Currents:

Effective value [Also known as Root-Mean Square (RMS) value] = 0.707 x peak value
Half Cycle Average value = 0.637 x peak value
Peak value = 1.414 x effective value
Effective value = 1.11 x average value

Resonant Frequency Formulas:

*Where in the second formula f is in kHz and L and C are in microunits.


Reactance Formulas:

Impedance Formulas:

Q or Figure of Merit:

Voltage/Current Phase Rule of Thumb:

Remember "ELI the ICE man"

ELI: Voltage (E) comes before (leads) current (I) in an inductor (L)

ICE: Current (I) comes before (leads) Voltage (E) in a capacitor (C)