Electromagnet Basics Fundamental

[Jiggy-Ninja]

yew_qi_ming:

1. Will it short circuit when positive terminal is arduino 5V, negative terminal is GND ?
   (I saw online many people just connect to battery at both ends)

Outside of super conductors, you will never see a truly short circuit (ie 0 resistance connection) in reality. Short circuits are a matter of degree, and what is appropriate for one circuit is not appropriate for another.

Wires inherently have some resistance, and thinner wires have higher resistance. Longer wires also have higher resistance, so as you wind the wire across the core you are accumulating resistance. Higher resistance = less current by ohm's law, and you can measure the resistance with a multimeter once you're done winding. Then it's just a matter of figuring out if that much current is too much for whatever you want to power it.

The Arduino's power regulator isn't good for much more than powering the controller itself and a few LEDs. It's too weak to power magnetics like this. Use a separate power supply for it.

2.Does the material need to be electric conductor ?
(I saw online they only use nails without giving reason)

The core material? No, it doesn't need to be conductive. It needs to be magnetic. Which usually means it will be conductive since most magnetic things are metals, but that's not important. Nails are usually used because they're cheap, common, made of steel (as long as it's not stainless), and round (good for wrapping wires around). If you have something else magnetic that you can wind wire around that you want to use as the core, knock yourself out.

3. Does the insulating layer of copper wire need to be removed? What are the suggested wire diameter
   (I saw online some people removed whereas some people doesn't)

NO!!!!! Absolutely not.

Magnetism is caused by current flow. Coiling a wire around something effectively multiplies the amount of current that is flowing around the area, which in turn multiplies the amount of magnetomotive force (yes that is a real technical term) applied to the magnetic core. More MMF = more magnetic force.

If you remove all the insulation from the wires, you destroy the coiling since current can flow straight across the coil instead of spiraling around it. As the others said, only remove the insulation from the very end of the wires so you can connect it to the rest of your circuit.

It also makes the "coil" have super-low resistance and draw massive amounts of current from whatever you hook it up to, risking destruction for any power supply that isn't designed to gracefully handle massive overloads.

[johnwasser]

yew_qi_ming:

1. Will it short circuit when positive terminal is arduino 5V, negative terminal is GND ?
   (I saw online many people just connect to battery at both ends)

If you connect it across power, current will flow through it. If too much current flows it can be considered a short circuit. More wire (more turns) or thinner wire (less conductive) will reduce the current.

yew_qi_ming:
2.Does the material need to be electric conductor ?
(I saw online they only use nails without giving reason)

If you mean the core, it doesn't have to conduct but ferromagnetic material (iron, most steel) will concentrate the magnetic flux. A large nail often makes a good core. The wire must be conductive or it isn't a wire.

yew_qi_ming:
3. Does the insulating layer of copper wire need to be removed? What are the suggested wire diameter
(I saw online some people removed whereas some people doesn't)

The wire has to be insulated, except on the very ends where you connect it to electricity. Some 'enameled' or 'magnet' wire has insulation that will burn off when you heat it while soldering. Some insulations don't burn and have to be scraped/sanded off at the ends.

You get more magnetism with more current (thicker wire) and more windings (thinner wire). You should pick the wire size based on how much current you have available, and how much space you have for the coil. The current will also be limited by how much the wire can carry before overheating.

[Grumpy_Mike]

Whandall:
Not if you mount the magnet above the "levitating" object.

Or use an opposite magnet (or magnet field like in maglev trains) that is much stronger than paramagnetic material.

Yes I know this but it is not a stable arrangement. I once had a physics student do this as a final year degree project and he struggled with it. He only achieved a few mm of suspension. Given the level of questions the OP is asking, he is ten years off being able to do that.

On the other hand there are a few instructiables projects ( that won’t work because they are poorly written) in a much simpler arrangement with paramagnetic materials like bismuth, which you can get from the lead free shot cartridges.