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In the 1800s scientist began to better understand how electricity and magnetism were connected. At this time, travelers used a compass which pointed to the north pole. Scientists began to see that their electrical circuits would change where a compass pointed. A surprising discovery! This observation was important but it did not show the theory that connected electricity and magnetism.
Electricity flowing through a wire creates magnetic fields. These fields can attract other objects. As electricity flowed, then the wire would become magnetic. These magnetic fields may be hard to imagine, but if you let metal settle over time you can see the fields. The experiment described below shows the fields created by a rare earth magnet.
Now, scientist talk about electricity and magnetism together, so they study “electromagnetism.” You have been studying electromagnetism this whole time!
Electromagnetism is the big idea behind observations about electric currents and magnetic forces. A changing electric field creates magnetism. And, changing magnetic fields will create an electric field. These fields move creating waves of electromagnetism. It’s impossible to separate electricity from magnetism!
Waves of energy have very different sizes!
Electromagnetic waves are different than ocean waves or sound waves. Waves that you can see and hear need to move water or air to travel. These waves need to be in something. Electromagnetic waves can be anywhere, even space (which is big and empty)! These waves have a photon. There is no matter in a photon, just energy. These little packets of energy move in waves across the universe, and even across your eyeball right now!
These waves can be as small as 1 millionth of a millimeter (0.0000000001 millimeters!). We use small waves like these to take X-rays. Other waves can be 100 meters long. We use long waves like these to send AM radio over long distances. Your FM radio uses waves that are between 1 and 10 meters long. The length of a wave makes it useful for different things.
Radios are a good example of how electricity and magnetism are examples of electromagnetic waves. The radio waves are electromagnetic waves. These waves are created by electricity flowing into a transmitter antenna which makes electrons vibrate up and down it, producing radio waves. Then, the radio waves move electrons in your radio’s antenna. (Yes, your car has a radio antenna, even if you can’t see it!). Your radio uses these moving electrons to understand the sounds sent by the radio tower. This is how your radio creates music!