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I'm doing an school experiment with my daughter and I made two alternating current generators. One is a coil of 22 gauge wire and the other is a coil of 28 gauge wire where we rub a strong block of neodymium magnet across.

The coil that has thinner wire produces more voltages and more current and lights the small led light bulbs brighter(about 2.7 volts, 0.201 amps, 47 ohms resistance when measured at the two leads after the coils)

and the one that has thicker wire produces less volts and less current and less resistance.(about 1.1 volts, and 0.181 amps, 8.3 ohms)

Both coils are made up of about 500 feet of insulated wire.

I initially thought that the one with thicker wire would produce more voltages or in any case more amps. But that wasn't the case, does anyone know why?

I've added a photo of the configuration for more clarity.

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  • $\begingroup$ At the current levels you're dealing with the difference in resistance between the two is negligible. $\endgroup$
    – Hot Licks
    Oct 13, 2019 at 2:33
  • $\begingroup$ Do the two coils have the same number of loops of wire? I would expect thicker wire might have fewer loops which would result in a smaller induced voltage. $\endgroup$
    – M. Enns
    Oct 13, 2019 at 3:37

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It is difficult to speculate, as you do not provide a picture of your gadget, so take the following for what it's worth.

The coil made of thicker wire will have greater dimensions, so maybe parts of it will be located farther from your magnets, so the magnetic field and voltage there will be lower for the same motion of the magnets.

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  • $\begingroup$ the thicker gauge wire makes for a larger coil yes. I would have assumed however that because the wire is thicker there would be more electrons flowing at a given point in the wire and thus the total current flow would have been greater. Not the case the resistance on the magnet is considerably less. $\endgroup$
    – sqljunkey
    Oct 13, 2019 at 4:48
  • $\begingroup$ @sqljunkey : The resistance of the thicker wire is indeed less, but I don't think this is important because I suspect the resistance of a lighted bulb is much greater than the resistance of the coil, so the resistance of the coil is negligible in both cases. You can check this experimentally. However, note that the resistance of the hot bulb is much higher than that of the cold bulb. "Not the case the resistance on the magnet is considerably less. " I don't understand this phrase. $\endgroup$
    – akhmeteli
    Oct 13, 2019 at 4:57
  • $\begingroup$ as I drag the magnet across the thinner gauge loop of wires I can feel a resistance in the magnet as I do the same with the thicker gauge wire I feel less resistance. $\endgroup$
    – sqljunkey
    Oct 13, 2019 at 5:13
  • $\begingroup$ This all means then that if I get a thinner gauge wire I would get a smaller loop and that will create more voltage ? $\endgroup$
    – sqljunkey
    Oct 13, 2019 at 5:14
  • $\begingroup$ @sqljunkey : You see, I don't know how your coils look, I don't know how you move your magnet. I only know that with thicker wire the coil dimensions will be greater. Maybe some turns of the coil are farther from the magnet in that case, so they are in a lesser magnetic field, so the voltage is less. $\endgroup$
    – akhmeteli
    Oct 13, 2019 at 5:36

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