What does it mean that a cable (for networking, or TV, for instance) has an "impedance of 50 ohms", for instance?
I understand that impedance (Z) is calculated as sqrt(R^2 + X^2). Resistance (R) is dependent on the length of the cable, and the cable might be cut to different lengths. Reactance (X), on the other hand, is frequency dependent. So what does the "50 ohms" (or whatever the value stated) actually mean?
TIA, Hilmar.
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