‘Ferrites’ are a class of chemical compounds with the formula AB2O4, where A and B represent various metal cations, usually including iron. These ceramic materials are used in applications ranging from magnetic components in microelectronics.

You normally see these “bumps” on the mouse, keyboard and monitor cables. You can also find them on power supply wires when a device (like a printer or scanner) uses an external transformer.

These “bumps” are called ferrite beads or sometimes ferrite chokes put to reduce EMI (electromagnetic interference) and RFI (radio-frequency interference).

It is a passive electric component used to suppress high frequency noise in electronic circuits. Ferrite beads employ the mechanism of high dissipation of high frequency currents in a ferrite to build high frequency noise suppression devices. Ferrite beads may also be called ferrite cores, ferrite rings, ferrite EMI filters.

These cables act as nice, long antennae for the signals they carry. They broadcast the signals quite efficiently. The signals they broadcast can interfere with radios and TVs. The cables can also receive signals and transmit them into the case, where they cause problems.

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