Useless fact
What is the cylinder on a laptop charger cable called?
The cylindrical bump found near the end of many computer and phone charging cables is called a ferrite bead.
The cylindrical object seen on many power cords and USB cables is a ferrite bead, also known as a ferrite choke. Inside the plastic casing is a hollow cylinder made of ferrite, a magnetic chemical compound composed of iron oxide combined with other metals. This component acts as a passive low-pass filter that suppresses high-frequency electromagnetic interference (EMI) in the cable. When electrical devices operate, they generate electromagnetic noise that can travel along cables and interfere with other electronics nearby, or vice versa. The ferrite bead works by absorbing these high-frequency currents and dissipating them as a tiny amount of heat, ensuring stable data transmission and power delivery. The design is a simple and cost-effective way to comply with electromagnetic compatibility regulations without needing active electronic components inside the cable itself.
Why this is true — This is verified by electronics dictionaries and encyclopedias which identify the cylinder on a cable as a ferrite bead or ferrite choke, used to suppress high-frequency noise.
Sources
- Ferrite bead Wikimedia Foundation