Why is there a black cylinder at the end of a charging cable
The small, black cylinder near the plug of your charging or peripheral cable is not just for decoration. It contains ferrite and serves as a shield against electromagnetic interference, ensuring that your gadgets run smoothly.
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How a ferrite core protects equipment from interference
This tiny cylinder has several names: ferrite bead, ferrite core, ferrite choke, or EMI filter. All of these names point to the same function: blocking electromagnetic (EMI) and radio frequency (RFI) interference. Inside is ferrite, a magnetic material based on iron oxide that absorbs high-frequency noise in a conductor. Manufacturers either put the bead on during cable assembly or snap it on later, placing it closer to the end.
When current flows through the wire, an electromagnetic field is generated around it that can interfere with neighboring devices, ranging from laptops to medical equipment. At the same time, the cable itself can pick up extraneous signals and "lose" data. Ferrite absorbs unwanted high-frequency vibrations and dissipates them as heat, allowing only the useful low-frequency signal to pass through.
Without such a filter, consequences can include monitor flickering, speaker humming, slower data transmission speeds, or even data loss. Thus, the black cylinder plays the role of a "silent guardian", enabling your laptop, printer, or monitor to charge without interference.
As a reminder, Meta — which owns Facebook, Instagram, and WhatsApp — is building the Waterworth submarine cable, which will be 50,000 kilometers long. That's longer than the length of the equator! The cable will contain 24 pairs of optical fibers and is expected to enhance the global infrastructure for artificial intelligence applications.
Despite the popularity of wireless technologies, we wrote that charging gadgets without cables is often not as convenient as it seems. Typically, it is inferior to wired charging in terms of speed, stability, and efficiency.