Impedance is a complex resistor-like term.
Resistor
Or with the complex impedance Z (a complex number):
where:
Capacitor
When we let U and I be:
or nicer:
where:
Inductor coil
Induction and magnetic flux Φ:
then the self-induced voltage is:
When we let U and I be:
Then:
or nicer:
where: