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I have an idea to DIY a little thing that would require to throw a piece about 20 cm into the air (straight up).

My idea is the following: To have a mini electromagnet (such as this one ) and to have a permanent magnet attached to the bottom of my piece. I'd first have the electromagnet pulling the piece, and then instantly switch the polarity in order to repel the said magnet and hopefully propel it upward.

And my question is: could this even work? Assuming the piece to propel is only the magnet, how big of an electromagnet and of a permanent magnet would it require?

Thanks.

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    \$\begingroup\$ What would stop your magnet flipping over to be attracted to the electromagnet again? \$\endgroup\$
    – Transistor
    Commented Aug 16, 2020 at 13:25
  • \$\begingroup\$ well, good point. The end goal is to have the magnet glue to the inside a 5 cm box. So this might be enough to prevent the flip? \$\endgroup\$
    – Tiller
    Commented Aug 16, 2020 at 13:54
  • \$\begingroup\$ I wouldn't think so. Electro-magnets are highly inductive. That means you can't reverse the current instantly. How much electrical theory do you know? Can you figure out how long it will take to reverse the current through the solenoid if you flip the voltage? If you can do that how does that relate to the amount of time it would take for the magnet to flip? Note that there is no datasheet for the device you are considering so you have no specification for the inductance. \$\endgroup\$
    – Transistor
    Commented Aug 16, 2020 at 14:00
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    \$\begingroup\$ "I'd first have the electromagnet pulling the piece". Why ? If you want the piece to go straight up as mentioned in the question, the permanent magnet will be resting on the (switched off) electromagnet due to gravity initially. Then, later, the electromagnet can be activated, pushing the piece straight up against gravity. No need to deal with current reversing. \$\endgroup\$
    – AJN
    Commented Aug 16, 2020 at 16:15
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    \$\begingroup\$ This probably is possible with a sufficiently energetic and rapid discharge. The coil may not survive, but that might actually be helpful. Note however that it's probably going to be easier to build something spring loaded either launched by releasing a hold down electromagnet, or with a solenoid that releases a physical hold down latch. \$\endgroup\$
    – Chris Stratton
    Commented Aug 18, 2020 at 20:04

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No, it can not. Or at least not with a 400N magnet and a "generic" round magnet

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    \$\begingroup\$ Incorrect. What you mean is that it cannot be done with that setup. But that setup is rather obviously weak... you can hear someone flip a little switch. A system actually designed to do this, would among other things be loud. That little switch would be welded or vaporized... in fact, the switching element might be designed to self destruct. \$\endgroup\$
    – Chris Stratton
    Commented Aug 18, 2020 at 20:00
  • \$\begingroup\$ The person in the video is I. The flip you can hear is the 230V power plug. The setup is 2 12V power supplies in serie with the magnet connected to them. And yes, obviously it can not be done with the setup I put in place but it might be possible with bigger magnets and possibly a big capacitor to ramp up the voltage like crazy. \$\endgroup\$
    – Tiller
    Commented Aug 18, 2020 at 20:16

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