# Magnetising a needle with static electricity using silk cloth

A nautical navigation textbook on my table says that we can magnetise a non-magnetised needle by rubbing it with a silk cloth. I decided to cross check on the internet, and found some experts calling it off as bullshit. They said that it will make the needle charged with static electricity, as the friction will cause the electrons to transfer between surfaces, and the force of a magnetic field does not affect a static object. So if any of you can conform/reject this notion, then please do.

Apart from that, I tried to make sense of the fact that a capacitor creates an instantaneous current when connected to ground. I also know that a magnet can be made by placing a ferrous demagnetised object in the center of a copper coil that has an electric current running through it.

So if we're stranded at sea with our compass demagnetised, can't we make use of two dissimilar materials by rubbing them, then connecting the resultant static charged object to a copper coil that is ground, placing a demagnetised needle in the center of the coil and finally, closing the switch to let the charged object discharge?

As a needle has such low volume and mass, I believe a few such discharging cycles could effectively find us north again!

Will this work?

P.s. If you close this question as off-topic, at the very least leave a reason.

[ EDIT #1 ] User @phillip-petty has suggested that the effect of self inductance in the coil will theoretically get rid of the possibility of (strong) magnetisation, due to the short time the current flows in static discharge. What if we use a hand-crank triboelectric generator - e.g. the one with a glass flywheel with a leather flap pressed against it? That will generate a current as long as you spin the flywheel and should overcome self inductance! And yet, no need for magnets to make a magnet.

[EDIT #2] I have been told that ROLLING the needle against the silk will magnetise the needle, as long as both objects keep their charge. The idea is that the opposite charges of both will always try to stay as close as possible, regardless of the needle's orientation. Thus, if we roll the needle, it is effectively moving the charge around it, just like an electromagnet's coils move electrons in the coil around the core magnet. I drew these diagrams for those who check out this post in the future. Can the experts confirm this notion? Will it magnetise the needle as intended?

• You know, I wanted to suggest the possibility of a hand-crank generator in my post, but I decided to keep it short. Faraday showed that you could electrolyze equivalent quantities of a solution using a battery of a given strength, and then cranking a triboelectric generator a certain number of turns. It seems like it would work in the needle case too. Commented Nov 15, 2021 at 15:17
• @phillip-petty I tried to find the Faraday demonstration you mentioned on the net but can't seem to find it. Are you sure he didn't use an electroMAGNETIC hand crank generator, rather than TRIBOelectric? Is there a name for that experiment or device he used so I could search it more specifically? Also, check out my new edit #2 and tell me what to you think of it. Commented Nov 17, 2021 at 1:15
• Sorry, I looked over my notes and found the section I was referencing. It does seem to be an electromagnetic generator. The references are in "Experimental Researches in Electricity" Volume 1, Third Series, Paragraph 290; then again in the Fifth Series, Paragraph 450. Commented Nov 17, 2021 at 2:01
• @phillip-petty So. What about the rolling of the needle against charged silk :P Commented Nov 17, 2021 at 7:06
• @ElFlea Why not to do some experiment instead of discussion? Commented Nov 21, 2021 at 18:13

First, an electron has both an electric charge -e and an intrinsic magnetic dipole moment N-S, μ.

Static electricity in the needle means that you rearrange the charges in the needle and you spatially split them in negative region (one end of the needle) and positive (other end of the needle). Negative region is the region which has an excess of free electrons where positive region is the region which has a lack in the number of electrons. This charge imbalance causes the electrostatic charge and field of the needle when rubbing it with a cloth.

However in this kind of charge the magnetic moments of the electrons are randomly scattered in any direction therefore there is no magnetization of the needle thus it CANNOT SENSE and respond to the magnetic field of the Earth.

Magnetostatics are different. Charges (i.e. electrons) are evenly distributed inside the matter of the metal needle. If you can find a way assuming the needle material is ferromagnetic to re-orient all magnetic moments of the unpaired electrons to align to the same direction then you will magnetize the needle and it will sense the magnetic field of the Earth and needle will respond by aligning to the magnetic field of the Earth!

See below illustration of the difference between electrostatically charged matter and magnetically dipole charged matter (i.e. magnetized):

Green arrows represent the magnetic moments N-S direction of the electrons.

It all depends on the material if it is magnetizable or electrostatic chargeable? There are materials that respond both to magnetic and electrostatic charging but eletrostatically charging a material will not make it magnetic and magnetizing it will not make it electrostatic.

Note: Even, when uniformly rubbing the needle with a cloth so that you end up with a uniformly electrostatically charged needle (i.e. the whole needle surface lacks in electrons or has an excess of electrons relative to other material objects), it will still have its charges' magnetic moments randomly oriented and therefore you cannot achieve magnetization of the needle by triboelectric effect. Electrostatic charging is about spatially transferring whole charges from one place to the other. Magnetostatic charging is about turning the charge's magnetic moments so that they face all to the same direction. It's two different things which each requires a different procedure to be accomplished assuming the specific material's atomic structure allows it.

Update 22 Nov 2021:

Although the above answer is describing the general case farther investigation revealed this article I cannot dismiss lightly since in almost every rule there are exceptions and we must be open minded:

Survival Gear: How To Make A Compass

It says: "you can magnetize a needle by rubbing it against your hair, some animal fur, or silk. Carefully hold the sharp point of the needle and rub just the eye of the needle 50 to 100 times against the hair, fur, or silk."

In first glance this may seem ridiculous but there is possibility to both electrically charge in this case the needle and also magnetize it!

This is because it says to only rub the eye, the very tip of the needle. It is possible in such as small volume (less than a few microns cross-section) the electrostatically accumulated charges in there to end up also more or less with aligned magnetic moments in the same direction. Therefore aligned magnetic domains are formed at the very tip of the needle that would act as a magnet.

Only an actual experiment can tell with the needle seeking the Earth's magnetic south pole (i.e. located close to the Geographic North pole).

I expect this magnetization effect to be very small, if any at all, but a needle floating on water, could work.

Update 26 Nov 2021:

I did an experiment linked on the comments below (please read also my related comments below addressed to @Ed Flea, to avoid any misunderstandings). Nothing conclusive unless repeated many times and replicated also by others, although it seems at first glance a positive result.

Update 28 Nov 2021:

Okay, I have repeated this experiment many times now and my results show conclusively that you CANNOT magnetize the eye of a needle by static electricity (i.e. triboelectric effect) as some of these survival guides magazines claim.

The first experiment run I've got a positive result must have been a fluke, somehow accidentally the needle must have been magnetized. I bought some new needles and repeated the experiment 10 times, always with the same result. No magnetization of the needle.

Conclusion: You cannot magnetize a needle by static electricity.

• I have updated my answer with an interesting twist I have found. I encourage everyone to do the actual experiment and report here back. If the experimental results turn out to be statistically positive, given my explanation to this effect, I suggest we name this effect as "El Flea effect" honoring the person here who brought the subject :) Commented Nov 23, 2021 at 14:50
• Of course there is also the possibility such an small spherical area to get magnetized from the own magnetic field of the Earth (~50μΤ) by swinging the needle 50-100 times and not due any triboelectric effect. Commented Nov 23, 2021 at 15:03
• If the material is ferromagnetic the domains are there already. You do not form them by an external process.
– nasu
Commented Nov 24, 2021 at 12:40
• And any experiment should check first that the needle is not magnetized BEFORE rubbing.
– nasu
Commented Nov 24, 2021 at 12:43
• Also make sure using a second identical needle and a magnet that your needle is ferromagnetic. If it is made out by stainless steel it cannot be magnetized. Commented Nov 24, 2021 at 15:34

Let's consider using a battery to create the current in the coil. To magnetise the needle, you would insert the needle into the coil, then connect the battery. Connecting the battery caused the current to change from zero to its maximum value which caused a magnetic field to build up inside the coil. When the battery is disconnected, the magnetic field falls to zero again.

During this process, the coil is also affected by self-inductance. Each section of coil experiences inductance due to the changing magnetic field created by the adjacent sections of coil. The self-inductance doesn't matter with the battery because the current flows long enough for the self-inductance affects to fall off.

In the case of using static discharge, the current doesn't flow long enough for self-inductance affects to fall off (I haven't tried to quantify this). I don't think one could achieve a significant enough charge by triboelectric affect to achieve a meaningful magnetic field inside the coil, but even if one could, I think the self-inductance of the coil would make the magnetic field negligible.

That being said, I haven't tried the experiment.

• To magnetize the needle as a compass needle by using a magnetic field the magnetic flux lines must be along the length of the needle. This is done by positioning the needle at the center of an electric solenoid. Just feeding the needle with current will create a concentric circular magnetic field around the needle perpendicular to the length of the needle which does not magnetize the needle after the current is cut. Commented Nov 26, 2021 at 6:55