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inertia
Should be working, but can't get this out of my head...
As I woke up this morning I was musing on a similarity between electromagnetism and gravity.
If you move a magnet near a conductor it induces an electric current. The rise of this current produces another field which tries to resist that current. Conversely, when the field dies away that tries to push the current along. This is not noticeable in just a single straight wire (unless it is very long and exposed to these fields over its entire length, like powerlines during a sunstorm), but if you wind a long wire into a small coil it becomes very easy to see. In fact this is the basis for a lot of our electronics.
The tuner in a radio uses a coil to retard high frequency electromagnetic (radio) waves. Because the coil resists fast changes of the current flowing through its wire, the higher frequencies lose strength. Couple this with a capacitor that retards low frequencies and you can choose a frequency somewhere in the middle that you want -- tune to a particular radio station's frequency. You can alter the coil's properties or the capacitor's to select a wanted frequency. In practice it is usually simpler to change the capacitor.
I find it helful to imagine the electrons sloshing back and forth in the wire like water in a pipe. Think of the water in the pipe being pushed and pulled by waves from the ocean so that it is frequently changing direction forward, backward, forward, backward. How fast the waves go through one cycle of changing direction is their frequency -- literally how frequently they move in one or other direction. A radio signal at 621kHz jiggles back and forth 621,000 times each second -- the waves push the electrons back and forth that often.
Imagine the electromagnetic field around a coil to be like a heavy fan in a water pipe. It resists the water passing, but doesn't actually stop it. When the fan has sped up and matches the speed of the water passing through the pipe it doesn't resist the water. But try to slow the water or reverse it and the fan takes a while to change and will try to keep the water flowing while it slows. The capacitor is like a rubber diaphragm in the in the pipe -- it doesn't like to pass lots of water in either direction, but if the water changes direction very frequently (high frequency) the diaphragm would hardly resist it at all.
So what is the point of all this?
I couldn't get the image of the heavy fan out of my mind. Inertia -- a tendency to resist movement, or once moving to resist a change in that movement. This is what an electromagnetic field does to charged particles. Could this relate to how a gravity field affects massive particles -- inertia?
OK, so there is not much more point to it than that coincidence, but it makes my mind itch. It seems curious to me that two fundamental forces act in this way. We know almost nothing of gravity, but we are masters of electromagnetic manipulation. Understanding one may throw light on the other. And once we understand inertia we may have the explanation of gravity.
I am sure others have noticed this similarity before. In fact I had wondered before about it when I was a schoolkid. But when I was waking this morning it felt sooo important.
I should just get to work. :)
As I woke up this morning I was musing on a similarity between electromagnetism and gravity.
If you move a magnet near a conductor it induces an electric current. The rise of this current produces another field which tries to resist that current. Conversely, when the field dies away that tries to push the current along. This is not noticeable in just a single straight wire (unless it is very long and exposed to these fields over its entire length, like powerlines during a sunstorm), but if you wind a long wire into a small coil it becomes very easy to see. In fact this is the basis for a lot of our electronics.
The tuner in a radio uses a coil to retard high frequency electromagnetic (radio) waves. Because the coil resists fast changes of the current flowing through its wire, the higher frequencies lose strength. Couple this with a capacitor that retards low frequencies and you can choose a frequency somewhere in the middle that you want -- tune to a particular radio station's frequency. You can alter the coil's properties or the capacitor's to select a wanted frequency. In practice it is usually simpler to change the capacitor.
I find it helful to imagine the electrons sloshing back and forth in the wire like water in a pipe. Think of the water in the pipe being pushed and pulled by waves from the ocean so that it is frequently changing direction forward, backward, forward, backward. How fast the waves go through one cycle of changing direction is their frequency -- literally how frequently they move in one or other direction. A radio signal at 621kHz jiggles back and forth 621,000 times each second -- the waves push the electrons back and forth that often.
Imagine the electromagnetic field around a coil to be like a heavy fan in a water pipe. It resists the water passing, but doesn't actually stop it. When the fan has sped up and matches the speed of the water passing through the pipe it doesn't resist the water. But try to slow the water or reverse it and the fan takes a while to change and will try to keep the water flowing while it slows. The capacitor is like a rubber diaphragm in the in the pipe -- it doesn't like to pass lots of water in either direction, but if the water changes direction very frequently (high frequency) the diaphragm would hardly resist it at all.
So what is the point of all this?
I couldn't get the image of the heavy fan out of my mind. Inertia -- a tendency to resist movement, or once moving to resist a change in that movement. This is what an electromagnetic field does to charged particles. Could this relate to how a gravity field affects massive particles -- inertia?
OK, so there is not much more point to it than that coincidence, but it makes my mind itch. It seems curious to me that two fundamental forces act in this way. We know almost nothing of gravity, but we are masters of electromagnetic manipulation. Understanding one may throw light on the other. And once we understand inertia we may have the explanation of gravity.
I am sure others have noticed this similarity before. In fact I had wondered before about it when I was a schoolkid. But when I was waking this morning it felt sooo important.
I should just get to work. :)