Admittedly I'm clueless when it comes to electrical engineering. I felt compelled to add a ferrite bead/choke/clamp to my computer's power cord since it was missing one. Would it be helpful? What kind should I get, or are most sold generally the same? Does the wire need to wrap around the ferrite bead, or can I just clamp on the bead and call it a day? Thanks a bunch!

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    \$\begingroup\$ A better question would be, "why do some computer cables need ferrite beads?". For the answer, see below from Olin. \$\endgroup\$ – Ale..chenski Dec 12 '17 at 17:29

A ferrite bead around a cable adds common mode inductance to the cable. The purpose is to increase the impedance of the cable at high frequencies. With higher impedance, less power can be radiated or conducted from the cable.

Whether your cable needs a ferrite around it depends on whether you need to reduce the conducted or radiated emissions at high frequencies. If it is for personal use, then there is little reason to bother.

If you are trying to sell a product, then you have to make sure it conforms to the emissions standards in whatever jurisdiction you offer it for sale in. In the US, these standards are defined in part 15 of the FCC rules. In Europe, you generally need to meet CE specifications.

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