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I am performing an experiment for school investigating the magnetic force of a solenoid. While doing this experiment I realized that I needed to connect the solenoid to the DC output of the power supply instead of the AC.

I am perplexed since for current induction, fluxtuations in the magnetic field are needed. I thought this would be the same "the other way round", i.e. using a fluxtuating current to create a magnetic field.

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  • $\begingroup$ If current passes you're producing electromagnetic fields, doesn't matter if they are AC or DC. The problem with AC is that it will oscillate, and with DC it sill stay steady. $\endgroup$ Oct 7, 2016 at 20:34

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To be fair, you don't actually need continuous DC current, but you do need a waveform that is always in the positive (or always in the negative) voltage range. An AC source with a simple half-wave or full-wave rectifier (4 diode) will work fine without the need for a transformer or DC converter. It is still DC, it's just unregulated. Note that a half wave rectifier will only let you use half of the energy, with the same voltage but a 50% duty cycle pulse train. It might cause issues, depending what you are doing.

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The important part is that the waveform does not go say from 0V to 12V to 0v to -12v etc... With AC, every time the voltage is positive the field will go in one direction, and in reverse when negative, so overall it is approximately cancelled.

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  • $\begingroup$ I understand your answer from a practical point of view, but I think a good/complete answer should encompass @QuantumBrick's comment to the question $\endgroup$
    – Dries
    Oct 8, 2016 at 22:23
  • $\begingroup$ Is that not what the last paragraph does? $\endgroup$ Oct 9, 2016 at 1:45
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To produce a steady magnetic field by a current in a coil you need a direct current. If you use an ac current the magnetic field would change with time and change direction every half period of the ac current.

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