There are electromagnets inside stereo speakers
When did people invent electromagnets?
In the early 1800s AD, about 200 years ago, scientists in Denmark and Britain figured out another way to make magnets. (These countries had a lot of scientists thanks to colonization, slavery, and control of trade).
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This way you didn’t need a lodestone. You could also make much stronger magnets. And you could turn the magnets on and off.
How do electromagnets work?
The new way is an electromagnet. An electromagnet works by using electricity to create a magnetic field in a piece of iron.
What is electricity?
And what are magnets?
What is a battery?
When you hook up a copper wire to a battery, electrons begin to flow through the wire. They move from atom to atom, from one end of the battery to the other.
Why use copper wire?
A project with copper
They keep going until they even out the negative and positive charges at each end of the battery. This makes a circle of electrons just like the circle of electrons inside an iron atom. And, just like the iron atom, that’s a magnet.
Why so many coils of wire?
To make the iron atoms strong enough to be a useful magnet, you have to line up a lot of them all going the same way. It’s the same with an electromagnet. You have to make lots of copper wire circles all going the same way. If you wrap these coils around something made of iron, the coils will act like a lodestone and make that iron into a magnet.
Big electromagnets
If you use thousands of coils of wire and a big piece of iron, you can make a very strong magnet that can pick up cars and huge machines.
Alternating electromagnets
But tiny electromagnets are also very useful, because you can turn them on and off by connecting or disconnecting the batteries. Alternating magnets make the electricity for your car lights and steering, power stereo speakers, hold fire doors open, and are inside all electric motors, like in a hair dryer or a washing machine.
