What is the difference between 75 Ohm and 50 Ohm coaxial cable and when should each one be used?

50 and 75 Ohm values refer to the impedance of the coaxial cable. Impedance is a measure of resistance, in the cable, to the flow of electrical energy. There really is no “good” or “bad” impedance, just the right impedance for your application. For 75 Ohm cable, the primary application is the transmission of a video signal. In the case of 50 Ohm cable, it is a data signal that is for the most part being transmitted. Simply put, 75 Ohm is for pictures and 50 Ohm is for information.