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The motor effect


A magnetic field is created when an electric current flows through a wire. Electromagnets have strong magnetic fields due to the coiling of wire around a soft iron core. Electromagnets are used in many appliances including electric bells and relay switches. When a magnetic field from a wire is placed into another magnetic field, it causes the wire to move. This principle is utilised in electric motors and loudspeakers.


When an electric current [current: Moving electric charges, for example, electrons moving through a metal wire. flows through a wire, it produces a magnetic field [magnetic field: Region of space where a magnetic force acts. around the wire. This magnetic field is only present while the current is flowing.

This effect is used in electromagnets. Wire is wrapped around a soft iron core, and an electric current passed through it. The electromagnet behaves as if it were a bar magnet, except that it can be switched on and off.

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