Radio waves are a type of electromagnetic radiation, just like visible light. But they are at the bottom of the spectrum, which makes them harmless to humans, because low frequency means low energy. (High-frequency and high-energy radiation such as X-rays or gamma rays is another story.) This is part of the reason why radio waves are ideal for wireless communications. They can also travel long distances and pass through obstacles such as walls.
So radio is more important than ever. But did you know that you can easily build your own radio transmitter and receiver at home using a few simple supplies? I’m going to show you how. It’s a fun project and a good excuse to explore some cool physics.
What is an electromagnetic wave?
In this regard, what is a wave? Imagine that you have a long string with one end tied to a doorknob. You stand across the room, holding the other end. Now, if you move your hand up and down, you will create a disturbance in the string, and this disturbance will move along the length of the string. this wave. Basically, waves transport energy without transporting matter.
What if I take the floss? In this case, you will look like a sad person shaking hands with an imaginary friend. Without the string, there is no wave. Waves need something to “ripple” into, they need a medium. You can’t have ocean waves without water. You can’t have sound waves in space, because there is no air to ripple them through.
But what if, instead of a string, you shook an electric charge (such as an electron) up and down? Electric charges create electric fields, so this Moving The charge will create an oscillating electric field, creating an electric wave. And here’s where it gets weird: It turns out that a changing electric field also creates change Magnetic area. The opposite is true: a changing magnetic field creates a changing electric field. We know this from Maxwell’s equations.
This means that we have electric and magnetic vibrations moving together, and each is a medium for the other. This combination is called electromagnetic radiation, also known as “light.” Yes, radio waves are just light, light He can It self-propagates through empty space, at the speed of light, in fact.
Piezoelectric radio station
Okay, let’s make a radio wave! For the transmitter, all you need is a barbecue lighter, you know, the kind with a long tube. When you hold down the trigger, gas is released through the end of the tube and ignites with a small spark. Here’s one I cut in half:
Photo: Rhett Allen
