All my life, I’ve wondered what the strange bump at the tail end of my laptop and phone charger is. Always, I’ve wondered why it’s put there and for what purpose? So, I went digging for answers, and here is all I came up with..
You normally see these “bumps” on the mouse, keyboard and monitor cables in a typical computer system found in a home or office. You can also find them on power supply wires when a device (like a printer or scanner) uses an external transformer.
What are these Bumps called?
It turns out that these bumps are called ferrite bead. It may also be called blocks, core, rings, EMI (electromagnetic interference) filters, or chokes. A ferrite bead has the property of eliminating broadcast signals and prevents energy loss of the same type within the charger. This makes the charger much more effective and helps charge your computer more quickly. Their purpose is to reduce EMI and RFI (radio-frequency interference). These cylinders are responsible for stopping very large deviation of power over supply through the cable and power surges in currents that pass through the cable and prevent ‘choke’ within the wire to make it any further supply the current to the device. The blocking is most effective when it is near the source of the EMI, that’s why you will only find these ferrite beads near the end of the cables.
It also acts as a choke or inductor that blocks high frequency noise in electronic circuits. Ferrite bead employs the dissipation of high frequency currents in a ferrite ceramic to build high frequency noise suppression devices.
The bead is made up of ceramic compounds, derived from iron oxide and/or oxides of other transition metals. It helps to prevent the wire behave on over floating current like aerials. It slips over the cable when the cable is made, or it can be snapped around the cable in two pieces after the cable is made. The bead is encased in plastic — if you cut the plastic, all that you would find inside is a black metal cylinder. This metal wire can possibly serve as an antenna by absorbing or releasing any radiation while passing current around it.
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The radiation released by the wires without the bead could cause interference with other electronic objects around them, which act as receivers of this radiation, for instance, causing noise in speakers. This phenomenon’s example can be seen when cell phones interfere with the signal devices such as radios and speakers, producing a recurring noise well known for electronic users.