5.87. Electromagnet http://www.ck12.org
5.87 Electromagnet
- Describe an electromagnet.
- Explain why electromagnets are very strong.
This crane is dangling a big round magnet that has picked up metal car parts in a junk yard. The parts practically
leap up to the magnet because it’s so strong. That’s because it’s an electromagnet.
What Is an Electromagnet?
Anelectromagnetis a solenoid wrapped around a bar of iron or other ferromagnetic material. A solenoid is a coil
of wire with electric current flowing through it. This gives the coil north and south magnetic poles and a magnetic
field. The magnetic field of the solenoid magnetizes the iron bar by aligning its magnetic domains. You can see this
in theFigure5.187. You can learn how to make an electromagnet at this URL: http://www.youtube.com/watch?v=e
mlzh9XXWgQ
Strength of an Electromagnet
The combined magnetic force of the magnetized wire coil and iron bar makes an electromagnet very strong. In fact,
electromagnets are the strongest magnets made. An electromagnet is stronger if there are more turns in the coil of
wire or there is more current flowing through it. A bigger bar or one made of material that is easier to magnetize also
increases an electromagnet’s strength. At the following URL, you can see an animation demonstrating how these
factors affect the strength of an electromagnet. http://www.schoolphysics.co.uk/animations/Electromagnet/index.ht
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