This is why a ferrite bead is inserted to a charger. It has the capability of blocking the emission of radio waves from the cable so that it uses electrical power for charging purpose only. A typical ferrite bead is formed through an insulated wire wrapped around a magnetic material just like it is shown in the picture below. In our case, the charging cable is the insulated wire and the ferrite cylinder is the magnetic material which together form a special kind of lump for the charger.