What exactly are radio waves? How are we able to transmit (cause) and receive them?


Looking for a specific, molecular explanation.

In: Physics

Radio waves are streams of photons. These are fundamental particles, but not matter like molecules. Photons can have many different frequencies, and a narrow band of those frequencies can be detected by our eyes. We call photons in those frequencies light. Radio waves are much longer, lower frequency than light.

We mostly make radio waves with antennas. At its most ELI5, an antenna is a wire made of conductive atoms, like copper. Electricity in the wire excites the electrons in these atoms, adding energy to the electrons. When the electrons relax to their resting state, they have to release the energy, so they produce a photon and it zips away at the speed of light.

Making a large or powerful radio signal is more complicated, you need a wire of the right length to spread out the excited electrons and you need the electricity to alternate at the right frequency, but it all builds on this effect. This is also related to how an LED works, but the LED makes photons in that narrow range we can see.