Characteristic Impedance vs Impedance

Hi,

It is explained million times in the internet and there are even a lot of youtube videos.
Is it really neccessary to expain it again?
I mean: All the information is already given. It (the physics) won´t change with time.

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In short:
The characteristic impedance (of a cable for example) is a physical characteristc. I does not depend on cable length and not on frequency (over a wide range).
It depends on the dimension of the wire pair dimensions (diameter, distance) and on the dielectric constant between them.
(It may be calculated by the characteristic [capacitance per length) and [inductance per length])
You need the characteristic impedance of a cbale for proper driving and terminating a signal line to get a clean signal at the receiver side without much echoing (ringing).

The impedance is a frequency dependent value. It uses the actual capacitance and the actual inductance, mabe even the ohmic resistance.
It may be used to calculate a voltage drop at a given current .. for example.

Klaus

I recommend to go through some internet documents and videos. Then please ask a more detailed question. Tell us what sources you refer to, what you understand and what you don´t understand.