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If we increase the number of turns in a coil, the resistance increases, to overcome this, we can use very thicker wire and keep the voltage low to keep the current constant, and by the formula, this should make stronger electromagnet even by supplying less voltage.

Here in this video -- https://www.youtube.com/watch?v=1Jm11C8vEiQ , the boy creates a stronger electromagnet by supplying less watts but more turns and more thicker wire.

The video looks legit, because all other videos of him are legit.

The only downside is the size will bigger, the bigger the size the more efficient the inductive machine will become.

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    $\begingroup$ how many parameters do you want to change at once? $\endgroup$
    – JEB
    Mar 6, 2021 at 15:43

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You forgot one parameter: Length. The magnetic field B is proportional to the turn density, denoted by n. n = N/L , where N - no of turns and L - length of the solenoid. So if you wish to increase the thickness of the wire, you wouldn't be able to fit the same number of turns in the same length. The turns will be less and hence the field. So only option remains is to increase the length, which in turn would keep the ratio N/L constant.

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What determines the electromagnet's strength is how much current is flowing in the wire and how many turns there are in the coil. Of course smaller, longer wire has more resistance and requires a larger voltage to drive the same current. Your choice of power supply will determine the maximum current that it can drive through a given resistance.

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  • $\begingroup$ If I keep that electromagnet in cold water to reduce the resistance, will it create stronger magnetic field with lower voltage? $\endgroup$
    – Yogie
    Mar 16, 2021 at 20:41
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    $\begingroup$ Probably. You can test it, but be careful! $\endgroup$
    – S. McGrew
    Mar 16, 2021 at 21:24
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You are talking about a transformer (which can step AC voltage up or down), but the power out is always a little smaller than the power in (due to resistive losses). The size depends on the power being delivered. The wires need to be big enough to minimize resistance, but with enough turns to give an adequate inductive reactance on the input and the desired voltage on the output. Solid state devices generally function with a low voltage DC. To minimize the size and weight of the step down transformer and and the filter capacitor; the power supply rectifies the incoming AC and uses that to drive a high frequency oscillator. At a high frequency, the transformer can have a much lower number of turns, and the low voltage output can be filtered by a much smaller capacitor. The stereo amp that I built (decades ago from a kit), had a fist size transformer and two fist size capacitors. Today, my laptop is powered by a small black box.

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