- 1). Reactance in an inductor (inductance is usually designated as L) is calculated as:
Reactance (L) = 2 x Pi x Frequency (in Hertz) x Inductance (in Henrys)
R (L) = 2 X (3.1416) X F X L
Ex: for a 5 Henry inductor at 1 KHz, R = 2 X (3.1416) X 1000 X 5 = 31,416 Ohms - 2). Reactance for a capacitor (capacitance is usually designated as C) is calculated as:
Reactance (C) = 1 divided by the total of (2 x Pi x Frequency (in Hertz) x Capacitance (in Farads)
R(C) = 1 / ( 2 X (3.1416) X F X C)
Ex: for a 10 microFarad capacitor at 1 KHz, R(C) = 1 / ( 2 X (3.1416) X 1000 X 0.00001) = 15.9 Ohms - 3). As frequency increases, inductive reactance increases and capacitive reactance decreases.
- 4). Impedance (usually designated as Z) in an AC circuit is the combination of resistance and reactance.
As far as calculating series or parallel resistances, impedance follows the same rules in an AC circuit as resistance does in a DC circuit. - 5). Resonance is a frequency where the reactance of a capacitor equals the reactance of an inductor in a circuit.
For our examples above, at 22.5 Hz R(C) = 707 Ohms, R(L) = 706 Ohms.
Source...