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I was thinking about electromagnets today and a thought popped up in my mind on what would be a very simple way to create an electromagnet.

Although I have not built and tested it, I am pretty sure that it will function as an electromagnet even though it will be a lot weaker in magnetic strength than a standard electromagnet.

Below is a drawing I made of this very simple design. The working principle is that an iron washer is cut in half and then one half of that iron washer is superglued to an insulated, current carrying straight conductor/wire. The half iron washer will function as an electromagnet when electrical current is applied to the wire.

enter image description here

Would this simple design function properly as an electromagnet?

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  • $\begingroup$ Why the vote to Close? $\endgroup$
    – user57467
    Commented Mar 7 at 11:42
  • $\begingroup$ You get a magnetic field from the current in the wire. The presence of magnetic material near the wire will change the specific shape of the field in that region, but that does not make the washer an 'electromagnet'. $\endgroup$
    – Jon Custer
    Commented Mar 7 at 14:52
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    $\begingroup$ No one disputes that the iron washer becomes magnetized and modifies the magnetic field around the wire, and there certainly could be an interesting question about the magnetic field or possible utility of this arrangement, but it is an opinion whether this constitutes an "electromagnet". (I wrote my earlier comment without having seeing @Jon-Custer's comment.) Another opinion says "The simplest electromagnet is just a wound coil on free space – called an ironless electromagnet". $\endgroup$ Commented Mar 7 at 15:49
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    $\begingroup$ The close votes are probably because the way you had written the question it seemed to be "opinion-based." Also, as originally written, the question included a bunch of superlatives ("simplest") which are difficult to determine (e.g., how do we know there is not some slightly "simpler" design). I took the liberty of making a few choice edits that may help get this question reopened. $\endgroup$
    – hft
    Commented Mar 7 at 16:50
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    $\begingroup$ @hft, thanks for doing that. That is a better question. $\endgroup$
    – user57467
    Commented Mar 7 at 18:43

3 Answers 3

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Yes, it does seem like this would be a simple way to create an electromagnet, since the usual concept of an electromagnet requires a magnetic field generated by a current carrying wire and an iron core of some sort. It would probably not be the most efficient design, but it would work and it would be quite simple.

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It would work, although would be very inefficient compared with almost any other way of making an electromagnet. If you wanted a larger field in the 'gap' then you could improve it a little by keeping both halves of your iron washer, and re-joining them as shown in the sketch below.

A version of this, in which a small Hall probe is inserted into the gap, can be used to measure the current carried in a cable.

enter image description here

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  • $\begingroup$ I think that’s a good idea. I will try different washer sizes and shapes to see what works best. $\endgroup$
    – user57467
    Commented Mar 6 at 22:56
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    $\begingroup$ And rather than super-glueing the cut edge, which would likely be pretty fragile, you could just glue a couple of thin sheets of cardboard, wood, G10 etc. to the faces of the washer. $\endgroup$
    – Penguino
    Commented Mar 6 at 23:00
  • $\begingroup$ No! Do not have a non-ferromagnetic gap between the two parts of the washer. Rather make the surfaces as smooth as possible with as much metal to metal contact and apply the glue outside. $\endgroup$
    – Farcher
    Commented Mar 7 at 0:28
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In principle, you could. This is basically an electromagnet with just a tiny bit of coupling (not even one full turn) between the iron core and the current-carrying wire.

However, it is simple and no trouble at all to just wrap the wire around the washer segment a few times, which tremendously increases the strength of the field in the gap between the cut faces of the washer. A hundred wraps and you'll have a practical electromagnet.

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