From my GCSE studies, near to the end of a module, I was told that when an electrical current flows through a conductor, a magnetic field will be induced. Can a magnetic field create an electrical current?

I ask this because I hear about "free energy" that uses a magnetic core to move a copper coil to create a current (which in turn, I guess, will aid the magnetic field in creating movement). For this to be possible, wouldn't the magnet need to be moved along the coil? In the example, the magnet is stationary.

I guess my actual question is (based on the answer to the original question) can a stationary magnet induce a current in a conducting wire?

  • $\begingroup$ See Faraday's law of induction. Only a changing magnetic field will produce an electric field. $\endgroup$ – John Rennie Jul 3 '16 at 17:49
  • $\begingroup$ Of course if the conducting wire is moving relative to the stationary magnet you can get an induced current. $\endgroup$ – M. Enns Jul 3 '16 at 18:02
  • $\begingroup$ "Magnetic current" meaning relative motion of magnetic dipole is purely hypothetical (because no magnetic monopoles have been reliably observed), but it is assumed that they would render Maxwell's equations symmetric up to a single minus sign. $\endgroup$ – dmckee --- ex-moderator kitten Jul 3 '16 at 18:07
  • $\begingroup$ @M.Enns Follow up question: if the copper coil was given some energy to spin, and produce a current, could that initiate some sort of readily flowing circuit? Or - since the wire is moving - will the direction of the magnetic field will have to change in relation to the orientation of the wire, in order to produce a continuous current? $\endgroup$ – T. Okai Jul 3 '16 at 19:10

A stationary magnet will not induce a current, but a magnet that is moving will induce a current

Currents are induced by the time derivative of the magnetic field (see faradays law) EM induction

Now there is the fun idea of relativity in that everything is in relative motion so viewed from a moving frame you will see a current but viewed from the frame where the magnet is at rest you will not see a current. Induction and Relativity

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