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(Okay so this question might sound trivial to all of you smart physicists, but stay with me and provide your opinion)

I have been seeing a lot of videos recently on the internet about how you can make a generator using a DC fan and by glueing neodymium magnets all facing the same direction on the blades of the fan, . Whenever you place a large magnet next to it, the repelling force of the magnets would cause the fan to move in a constant motion and spin. The fan in motion would spin a motor and could generate small amounts of current.

A lot of physicists on the internet said that this is impossible and the videos are fake. I was curious and wanted to try it so I replicated the experiment and had no success. I don't know much about the physics of magnets, but wouldn't this "theoretically" work? I mean, you couldn't generate free energy from it according to the law of conservation of energy and mass, but is it possible to use magnets to cause a motor to spin? Why is it impossible?

If this method isn't possible is there perhaps another way that this could work?

https://i.stack.imgur.com/BtbL7.jpg

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    $\begingroup$ Totally bogus (but here is a link to one of the videos). $\endgroup$
    – Hot Licks
    Mar 12, 2018 at 22:26
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    $\begingroup$ It's really the same idea as this one, which is a lot clearer about how silly the idea is: youtube.com/watch?v=onmaz6mE-QI $\endgroup$
    – hdhondt
    Mar 12, 2018 at 22:34
  • $\begingroup$ Just for fun: I've gotten this to work: youtube.com/watch?v=WI0pGk0MMhg . And a generator is basically a motor backwards, so with some adjustments you could probably turn it into a generator with weak output. $\endgroup$
    – R. Romero
    Jan 12 at 22:25

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Props for actually trying it yourself! You basically answered your own question, though - it isn't possible because causing the fan to spin with a static magnet would violate conservation of energy.

The main problem is that if you get it spinning, each magnet spends some time attracted to the one in your hand and some time repelled from it. On average, it cancels out.

If you timed it right, you could get it spinning by moving the magnet in your hand. The energy required comes from the work you do with your hand, so there's no violation of energy conservation there.

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to make a "free-energy" or "overunity" motor using permanent magnets only is physically impossible and the reasons why are well-known to everyone except the people who make youtube videos like the one you saw. furthermore, it is not possible either to get the idea to work by some other method- no amount of cleverness can overcome the basic physics in this case.

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  • $\begingroup$ I think the people who made the videos knew it better than anyone else. (But certainly one can "overcome basic physics" by cheating somehow.) $\endgroup$
    – Hot Licks
    Mar 13, 2018 at 0:33
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since you already made it and tried it, you might want to try the following for a better understanding: there are glasses/liquids/materials which can visualize magnetic fields. put one over your design and watch the shapes of the magnetic fields. the main problem with such a design when only looking to the idea of it without using any laws that say certain things aren't possible would be that the magnetic fields tend to be quite even/rounded. this means that before the magnet on the fan passes the magnet you are holding it needs to push as much energy as it will later receive, in general. this is the same principle which makes magnetic gears so efficient, since they do not have physical contact bun instead work purely on those forces, so the energy they lose(excluding medium resistance, quantum effects, bearing friction, and other such things) they will also gain back. such a gear might lock in a preferred state due to misfabrications, but all energy comes back once it starts moving(energy lost due to the magnetic push.

however I highly recommend not following what I said, since testing and seeing it yourself might be really good for your understanding. and limiting yourself to someone else's understanding would be not that smart. perhaps you might even find/see something that could make a device like that somehaw/someway possible. remember physics and mathematics are far from complete, and you can get energy out of something you do not yet know exists.

so my main recommendation is to get or make such a lense or liquid/powder, you could even make it using ink/oil, and/or iron/magnet particles, you can also get magnetite from a river if you are going primitive. in general you can use a small transparent plastic lid to put it in.

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It works very well when connected to a dynamo. Any rotation that turns the motors core, such as a hand crank radio employing a dynamo, Would work just as efficient, providing what the magnets grade is. The MDOe - 42 are.

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  • $\begingroup$ Correction to my last statement: It is MGOe - N42 $\endgroup$ Jan 12 at 21:11
  • $\begingroup$ As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center. $\endgroup$
    – Community Bot
    Jan 13 at 0:32

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