Believe it or not, you are surrounded with a whole lot of electromagnetic waves. Your Mobile Phone, Internet Data Card for that matter, every wireless device within your proximity, communicates through these waves. These are one set of waves, but they aren’t all.

You must have seen a lot of wires in and out of your computer. Most of us certainly know what each wire is meant for, but there’s something we have been missing out. It isn’t because it is invisible or something like the earlier mentioned set of energy waves, but let’s not brood over it. This is article will help you step forward in unraveling the mystery of the black bead present on your laptop charger cable. Yes, it isn’t only limited to your laptop chargers, but also the display connectors, and on other peripheral connectors have these on them.

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What Is This Bead?

This bead or lump is called a ferrite bead, or simply, a choke. This is the technical name for a electromagnetic wave bouncer. But now, why do you think a electromagnetic wave bouncer is of any use in these cables?

The answer lies in the basic principles of the current flow through a conducting wire. As current flows along a wire, there is an induced field perpendicular to the direction of the current flow. This is electromagnetic interference (EMI) and almost every electronic device during its operation produces EMI.

For example, when you connect a mobile phone to your computer, there is some disturbance observed on the monitor in the absence of the ferrite bead. This could appear smooth, but on the long run could completely damage both your mobile phone and PC. Due to this very reason, there always is a special unit in all electronic manufacturing companies which monitors EMI produced from different devices. If at all this EMI exceeds a certain limitation, there is notable degradation of performance of gadgets and it could also lead to medical complications.

What’s Inside That Bead?

If you’re thinking about any complicated circuitry which could decrease the EMI being produced, you are wrong. There’s simply nothing in this choke.  When cut open, this bead consists of a cylindrical ferrite rod, magnetic in nature. The magnetic nature of this ferrite rod is what absorbs all the EMI and dampens these waves from interfering with the other devices.

This black bead is generally located closer to the EMI source hence in laptop charger cables, it is located close to the end of cable. So, in a nutshell the bead at the end of your laptop charger is simply a EMI blocker which protects devices from getting damaged due to the EMI. That’s it.