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The difference between impedance and resistance

My Dad would be ashamed for me for writing this thread (he had a background in electrical engineering) but can someone explain the differnce between impedance and resistance (other than the former is for ac and the latter dc) as it pertains to audio circuitry?
russellrcncom
shadorne's avatar
shadorne
7,491 posts
 
As to inductance the motion of a charge (which is current) causes a magnetic field.

Agreed. And the magnetic field can be shown to be a relativistic effect (Einstein - special relativity) of the pure electrical field. It all depends on your frame of reference.
6550c
393 posts
 
To dumb it down.

Resistance(R) => DC circuits design.
Impedance(Z) => AC circuits design.

Impedance includes resistance(R) + capacitance(C) OR - inductance(L). (BUT you cant have C and L at the same time)
almarg's avatar
almarg
9,670 posts
 
BUT you cant have C and L at the same time
Actually, that's not correct. A real-world (physical) capacitor will have some small amount of stray inductance, and a real world inductor will have some small amount of stray capacitance. Both will also have some non-zero, finite amount of dc resistance (the resistance of an ideal inductor is zero; the resistance of an ideal capacitor is infinite).

The magnitude and phase angle that define the overall impedance of a combination of resistance, inductance, and capacitance are calculated for a specific frequency as described near the end of my first post in this thread.

Best regards,
-- Al
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