I really can’t grasp the concept of waves. I can imagine it a bit for sound waves: a speaker has a surface that pushes air, and the moving air eventually pushes the membrane in our ears.
But I’m confused about wifi etc. What exactly is the thing that physically travels? Is it air or something else? Does it physically move in a wavy pattern?
Edit: thanks for all the answers! But damn I’m overwhelmed. It’s gonna take me days to read and fully understand the answers. But thanks!
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If you’ve played with magnets, you know that (for example) the North pole of one magnet has a region of space close to it that will repel the North pole of another magnet. This “magnetic field” is stronger, closer to the magnet.
A related thing happens in the experiment you might have seen, where someone (on an electrically insulated pad!) touches a high-voltage machine and their hair stands up. Similar charges on different strands of hair repel each other. This is called an “electric field”, and it’s stronger closer to the charges — often electrons in everyday situations.
Now these two fields are directly related to each other, because a *changing* magnetic field will create an electric field, and vice versa. A guy named Maxwell figured out a set of equations for this. One thing that popped out of the equations was that you could play with the numbers and come up with a velocity, the speed of light, which has been experimentally verified. So changes to these fields are key to how they relate, and the changes travel at the speed of light.
Now if you put an Alternating Current on an wire not connected on the other end (aka an antenna), the electric charges first try to rush in, and kind of bunch up at the end of the wire in a subatomic traffic jam. The moving electrons make a magnetic field. Bunched up electrons make an electric field. Since the current is alternating, it’s constantly changing and in fact reversing. So as the electrons flow away from the end of the wire, the electric field gets less intense–and this change in the electric field travels away from the wire at the speed of light. At the same time, the magnetic field reverses, and this change also flies away from the wire at the speed of light.
So off through space goes this changing magnetic field, which recreates a changing electric field, which recreates a changing magnetic field, which recreates …
And for certain frequencies, you call this disturbance a radio wave–or for higher frequencies, light, or X-Rays, etc.
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