How is electricity produced by a electromagnet?

avito009

I know that an electromagnet is made from a coil of wire which acts as a magnet when an electric current passes through it. Often an electromagnet is wrapped around a core of ferromagnetic material like steel, which enhances the magnetic field produced by the coil.

Does that mean that first current has to pass through the coil? Or is it this way: The iron core moves in a coil of wire and then electricity is produced? Or is it that first current needs to be passed in an wire coil and then when iron core is moved within this wire coil electricity is produced for distribution?

avito009

Battery

I think I have the answer. Initially the current is supplied through a coil of wire which turns it into an electromagnet. Now this current is provided by a battery. Then when an iron bar is made to move inside the coil of the wire it creates electricity which is supplied to the houses via the power station.

topsquark

Forum Staff
I think I have the answer. Initially the current is supplied through a coil of wire which turns it into an electromagnet. Now this current is provided by a battery. Then when an iron bar is made to move inside the coil of the wire it creates electricity which is supplied to the houses via the power station.
Specifically, moving the iron bar creates a magnetic flux in the electric coil. That produces an electric current in the coil.

-Dan

HallsofIvy

I think I have the answer. Initially the current is supplied through a coil of wire which turns it into an electromagnet. Now this current is provided by a battery. Then when an iron bar is made to move inside the coil of the wire it creates electricity which is supplied to the houses via the power station.
No, there is no battery that supplies electricity to the coil. Any time a wire passes through a magnetic field, or a magnet passes a wire, a current is induced in the wire. It is the motion of the battery through the coil that induces a current in the coil and that is the electricity that is supplied to the house.

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Woody

A slight slip of the keyboard from HallsofIvy:
It is the motion of the magnet through the coil that induces a current...
On a simplistic level you can think of the magnet "pulling" the electrons around to create the current.

I note that in your initial post you mention a ferrous core rather than a magnet,
If you place a ferrous core in a current it will become magnetised,
If you move a magnet in a coil it will produce a current,

If you move a non-magnetised ferrous core in a coil,
then the small naturally occurring magnetism of the core and the coil (in the earths magnetic field) will create small currents.
The key is that these small currents will induce magnetism in the core,
this induced magnetism will reinforce the small currents,
so although you start off with an un-magnetised core in a coil carrying no current, you will end up with magnet in a current.

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Woody

An alternative way of viewing this to consider the coil and the iron core at rest (with respect to each other).
Here all the electrons in the system are settled in a stable electro/magnetic field.
When the coil and core are moved with respect to the other, this stable arrangement is distorted.
This distortion creates a restorative tension in the electro/magnetic field which acts against the motion to try to re-establish a stable arrangement.