What is under impedence?

Question

What is under impedence?

Answer 1

Well, I haven't heard of it called "under" impedance, but low impedance. As opposed to high impedance. If this is what you mean, then impedance is nothing more than AC resistance. It's the combined resistance of all the caps, coils, and resistors, in a circuit. If the impedance is to low, it can do things like load down the output of your circuit and possibly damage the circuit, or cause the circuit to not work right. The impedance of a circuit needs to be "matched" to the load or the load should be "higher" than the circuit to prevent this issue. I hope this answers your question