What happens to an electric current produced from an electromagnet when the direction of the magnetic field changes?

Question

anonymous · Answer

Take a simple electromagnet like a coil. The current going through the coil depends on the magnitude of the magnetic field alongside the coil. What will happen to the magnetic field alongside the coil if the direction of the field changes? And how would that effect the current?

vincent-lyon.fr · Answer

Wording of question is too ambiguous. If magnetic field is fixed, no induced current will be observed. If magnetic field changes, then current will appear.

anonymous · Answer

@Vincent-Lyon.Fr : Even if the magnetic field is fixed, I think there'll still be a current. Ampere's law for example does not seem to mention any requirement that the magnetic field is changing.

stormfire1 · Answer

@leonice17: The short answer is that the current will reverse direction (assuming there is a changing magnetic field to induce the current to begin with). @slotema: If the magnetic field isn't changing there will be no induced EMF and therefore no induced current - see Faraday's Law of Induction: http://en.wikipedia.org/wiki/Faraday's_law_of_induction The direction of the induced current can be found from Lenz's law which states that the magnetic field generated by the induced emf produces a current whose magnetic field opposes the original change in flux. http://en.wikipedia.org/wiki/Lenz's_law

anonymous · Answer

The magnetic field would constantly change, that's why the AC current is converted to DC current