How to distinguish the positive and negative poles of indoor optical cables
Some are non-polar and function in the same way regardless of the direction of current through them. For terminals of such polarized electrical devices, the anode/cathode terminology is used, with anode being the con. According to master electrician James Hornof, for DC power, the red wire is generally positive and the black wire is usually negative. When you're dealing with electrical wiring, it's important to know which is positive and which is negative—but how are you supposed to tell them apart? The easiest way to tell is by looking at the color, but the colors mean different things depending on what kind of power is being used. By analogy, when in electronics a signal is observed across two terminals, the measurement of voltage between the terminals yields opposing signs for the positive and negative polarity.
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