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Impedance vs Resistance

To put into terms that those other than electrical engineers might understand, I like to think of it this way:

In a loop circuit in which the only component is a simple resistor, that resistor is the only thing in the loop that actually "resists" current flow. Apply a DC voltage to a loop without that resistance and current quickly rises...not to theoretical infinity...but until the wire melts or breaks..because the wire (not a perfect conductor) is a resistor itself.

When a DC voltage is applied to a more complex ciruit that also includes reactive components...such as inductors and capacitors...there won't be any current flow at all because there is no conductive path through a has a gap in it. But when AC voltage is applied, current will flow, rise, fall, reverse direction, and repeat. But in this case what is it that "resists" the current flow so it does not run wildly high?

In this case, yes, the resistor does provide such, but SO do the other reactive components. Together, but in a complex way, they "impede" the current flow and we refer to the value of the complex attribute as "impedance". Further, since the actual obstruction to current varies during the frequency cycle of the applied AC voltage, there is no one number than can represent the "resistance". Using the word impedance denotes not only that there is reactive "resistance" to current flow, but ALSO that it is a value that expresses a sort of RMS average of the momentary "resistance values" that occur as the current cycles through its phases.

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