I have a very sharp HS intern. I was trying to explain impedance to her and I quickly discovered that I understand it well enough for myself but not well enough to really explain it or teach it. Can someone point me to some resources for teaching this concept?
It depends on how deep you want to go-but here is a starter.
Resistance is the opposition to the flow of DC current.
Impedance is the opposition to the flow of AC current and has 3 elements-resistance-inductance and capacitance-each which has its own phase aspect.
These 3 will add/subtract together (depending on the phase) to give a final impedance number.
This could be either purely resistive-capacitive or inductive or any combination of them.