Some cables have a small cylinder on them, what is it for?
A large cylinder-shaped bulge at the end of your laptop cable cord may have never caught your attention. This cylinder is known as a ferrite bead, ferrite core, or sometimes, choke. Cables function as unintentional antennas, broadcasting or taking up electrical interference, a.k.a. noise. But do you have any idea what are these cylinders for?
The main purpose of this cylinder is to keep such electromagnetic interference at bay. As a result, the ferrite core is usually trying to reduce cable interference, often to meet regulatory standards that limit how much interference a device can emit. Electromagnetic interference, for example, occurs when your cell phone comes close to a speaker and you begin to hear strange noises in your call.