OHM'S LAW

• The strength of an electric current varies directly with the electromotive force (voltage) and inversely with the resistance. So I = V/R or V = IR where V is voltage, I is current and R is resistance.

• The equation can be used to calculate any of the above values when the other two are known. When R is calculated, it may represent resistance or impedance depending on the type of circuit being used (AC/DC)

• Resistance: The opposition to flow of direct current. (ohms, Ω)

• Reactance: The opposition to flow of alternating current. (ohms, Ω)

• Impedance: The total of the resistive and reactive components of opposition to electrical flow. (ohms, Ω)

• The reactance of an inductoris high and comes specifically from the back electromotive force that is generated within the coil. It is, therefore, difficult for AC to pass.

• The reactance of a capacitoris relatively low but its resistance can be high; therefore, direct current (DC) does not pass easily.