Complex opposition to AC: Z=R+jX with reactances jωL and 1/jωC.
Impedance Z=V/I=R+jX combines resistance and reactance, in ohms. Series adds, parallel by admittances. Magnitude ‖Z‖=√(R²+X²) and phase φ=atan(X/R). Inductive loads have positive phase.
R=30 Ω with X_L=40 Ω gives Z=50 Ω at 53°.
Impedance is the AC generalisation of resistance, and it is the quantity that decides current and phase in every AC circuit.
Complex opposition to AC: Z=R+jX with reactances jωL and 1/jωC.
Impedance is the AC generalisation of resistance, and it is the quantity that decides current and phase in every AC circuit.
One over j omega C, a reactance that falls as frequency rises, which is why capacitors pass high-frequency signals more readily.
J omega L, a reactance that rises with frequency and blocks high-frequency signals.
Typical applications include calculating the current drawn by a motor coil at mains frequency, designing a matching network with a specified impedance and predicting how a loudspeaker's impedance varies with frequency.
Study "Phasors" first (topic 39 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Admittance Y=1/Z. Ohm's law holds with phasors. RLC combos.
R=30 Ω with X_L=40 Ω gives Z=50 Ω at 53°.
The next topic is "Reactance", which builds directly on this one.
It is classed as Intermediate in Electrical Engineering (topic 40 of 106). It is an intermediate topic. Work through the beginner topics in Electrical Engineering first.
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