That small black lump on your charger cable is a ferrite bead, a vital component that filters out electrical noise. This ...
The small black cylinder near the end of many power and data cables is not a decorative lump of plastic, it is a deliberate ...
Simple, two-terminal SMT (surface-mount-technology)-ferrite-bead components perform crucial functions in many systems. For example, one might suppress electromagnetic emissions from a power wire.