What is impedance?

[flat5]

"you think i'm saying wrong things to metropolis?"

That's why I butted in, yes.
My only complaint was using the term "power" in your def. of Z.
Only reactance and resistance is directly involved, IMO.
You keep defending the use of power in the definition

Power is important when considering the pratical implications of impedance.
You are right to point this out.

"impedance Z is the resistance on AC"
Fine! Leave the def. at reactance and resistance.

"connecting low Z output to high Z input it is called bridging and
insures good match between the two of them... meaning less stress to the source,
low distortion etc."

"insures good match" is slightly confusing or misleading semantic-wise.
Here is a page that explains it all better than we have, IMO

Impedance FAQ

Please don't misunderstand me, I know you know a lot about impedance.
I just did not agree that power should be in the def. of it.
That's all. ok? Perhaps I'm wrong.

 

[metropolis]

that's a nice FAQ link there flat5..
so i guess it all comes down to: impedance is resistance in AC circuits and therefore has to be considered in the analysis.

i had little questions since we were talking about audio.. sometimes with a cheap speaker, if i turn up the volume to the max, i hear distortion as if the speaker is about to blow up..
does that mean i am exceeding its impedance range? or does it just mean i'm feeding an extremely high current to the speaker?
if i want to fix the problem, do I need to get a speaker with higher impedance range?

 

[audioguru]

I have never overloaded a cheap speaker so I don't know what noises it makes when its coil former hits the magnet structure or when its cone twists.

A speaker has a voice coil that is made from many turns of thin wire. When too much power is fed then the wire gets very hot and might melt. A speaker with a higher impedance will use less power so it will not be as loud and it will not be as hot.

If you turn up to max the volume of an amplifier then its output clips (goes up and down to the limits of the power supply voltage) which causes severe distortion.

 

[whiz115]

Please don't misunderstand me,.

i'm not... don't worry!

i'm still new and i'm still learning!

 

[metropolis]

thank you audioguru, and everyone else