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Ferrite Bead: Tiny Cylinder in Power Cords & Cable. Why?

What is the Tiny Cylinder in Power Cords & Cable?

Have you ever noticed a little cylinder in the shape of a lump in a power cord and cable? Have you ever seen the same in your laptop charger cord, USB cord, Mobile charger cable cord, Printer Cord, Monitor cord, etc. even in Mouse and keyboard cable cords? Today, we are going to tell you the secret story behind Ferrite Bead.


Theoretically, this Tiny Cylinder in Power Cords & Cable is ferrite choke or ferrite bead as shown in the above image.

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The ferrite choke is an object in the cylindrical shape, which is made up of Ferrite material (which is a magnetic material). A typical Ferrite choke (e.g. Solenoid) consists of an insulated wire around a magnetic material. In our case, the cable is an insulator and the ferrite cylinder is magnetic material to make a special kind of lump for the power cable and cords.


Ferrite Bead (or Ferrite choke) plays a very important rule. As we know, when current passes through the conductors (inside the power cords), it produces EMF (Electromotive Force) or Radio Energy. The power cords and cable transfer this energy outside in the form of noise, which disturbs and interferes with other electronics devices such as nearby radio sound that would be noisy with improper tuning of the channel.

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In addition, some electrical energy is wasted in the form of radiation, which also reduces the supply power to the battery or other connected devices, which leads to an increase in the charging time of the battery.


Ferrite Bead has the ability to stop and block the emission of radio waves from the power cords and uses electrical energy for charging purposes only without power losses. Due to this important factor, that’s why there is a tiny cylinder in your laptop or mobile charger cords. Now, I think it is enough because you have a clear understanding of the purpose of this magical tiny object (ferrite bead or ferrite choke) in the cylindrical shape in power cords and cables.

You may also read the following related but interesting questions and explanatory answers.

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  1. Gopakumar says:

    Hello, I dont think connecting a ferrite core inductor will stop emissions and all.. Rather, within my knowledge these inductors will stop the noise that get added to main signal/current flowing through the wire. Also ripples in the signals can be removed with these inductors.

    1. JohnConnor says:

      Does the ferrite bead act like a common mode choke in reducing the noise added to the main power supply?

    2. You are both correct. A ferrite bead can be used to reduce EMI coming from a cable (emissions) AND to reduce the effect of externally generated EMI on the integrity of the signal in the wire (immunity). If anyone is actually interested in the usage of ferrite beads, wikipedia has a much more complete article. This one is sorely incomplete…

    3. rahul kumar says:

      i think the ferrite core inductor acts like a filter to reduce the ripples in the signal , an din this way it also diminish the effect of AC signal and reduces the noise produced by the fields.

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  3. jorge l ramos says:

    me encantan sus publicaciones ayudan a conocer mas de electricidad y componentes

  4. Tom Smith says:

    I am looking for an blog who can elaborate some basics and major part of electricity.

    And when i am coming on your blog so my searching is end.
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  5. Nice articles about different unknown technical facts in a simple way to understand even for the lay man also.nice articles&I wish to read such articles always coming in fb or any other messages.tnx for the articles.

  6. Devinder saini says:

    Very useful article. Even I was also think about this thing million of times. Thanks again.

  7. All wrong. This cylinder is a filter that removes high frequency noise from a signal. In no way it can prevent EM wave propagation in connected wires.

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