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Electromagnets
Beginner
Soft iron cores concentrate field from a coil.
A coil with a soft iron core creates a strong, switchable magnet. Field ∝ NI. Used in cranes, relays, loudspeakers and MRI.
Scrapyard cranes lift cars.
Soft iron loses magnetism when current stops.
In more detail
An electromagnet is a coil wrapped around a ferromagnetic core, which produces a strong field when current flows. It can be switched on and off, unlike a permanent magnet.
Real-world uses
- Scrapyards use electromagnet cranes to lift metal.
- Relays and doorbells use electromagnets to move contacts.
- Electric doorbells and cranes in scrapyards use electromagnets that can be switched on and off.
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Frequently asked questions
Why use an iron core?
It concentrates and enhances the field by a large factor.
Can it be made stronger?
Yes, with more turns or a larger current, up to saturation.
Why does an electromagnet need an iron core?
The iron concentrates the field lines and increases the overall magnetic field produced by the coil.
Related topics in Magnetism & Induction
Ferromagnetism and domains · Hysteresis · Curie temperature · Permanent magnets · Magnetic flux · Faraday's law