How do Electromagnets Work?
The construction of an electromagnet is very simple. A conductive wire, usually made of copper is wrapped around a piece of metal, in this case iron. Now with the help of a battery a current is introduced. This current starts flowing through the coiled wire, resulting in the creation of a magnetic field. This magnetic field magnetizes the iron metal. Thus resulting in the creation of an electromagnet.
An electromagnet is similar to a magnet, it has two poles, like poles repel each other while opposites attract. Also it is able to attract iron filings. The only difference is that the magnetism is not permanent, once the current is removed, magnetism may stop working suddenly or after some time. An electric bell is a good example of the use of an electromagnet.

Reference:
https://science.howstuffworks.com/electromagnet.htm

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