The kind of magic without which all of this wouldn't be possible. This tag should be used for questions about the **physics** of the fields that charged particles create and how these fields interact. It should not be used for all questions involving electromagnetism; that would be everything on the site.
Questions tagged [electromagnetism]
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Why don't electrons take the shorter path in coils?
Below is a copper coil, presumably forming an electromagnet. From my understanding the electrons travel around the coil to produce a magnetic field. But why don't the electrons jump the wires and take the shortest path?
Below I tried to draw the…
rrswa
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Why isn't there a potential difference across a disconnected diode?
I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere.
The reason I ask this though is that from my…
Blue7
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How fast does electricity flow?
I get confused on the low-level physics of electricity from time to time. It came up in "Which way does electricity power a circuit," and I don't totally get it.
How fast does electricity flow? Is the speed of an electron different in say a resistor…
travisbartley
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What is the difference between the magnetic H field and the B field?
Wikipedia provides a mathematical explanation. Can I get the intuitive one? I'd like to, for example, understand a ferrite datasheet. These usually have graphs of H vs B, and the definition of permeability depends on understanding the relationship…
Phil Frost
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What is the speed of "electricity"?
In a distribution grid, what is the speed of
energy
signal
Is it strictly the same?
And how is synchronisation achieved? Is an electric grid essentially an orchestra where everyone is the chief and gives the beat to everyone?
curiousguy
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Stealing energy from radio towers or power lines
From this answer: How much energy can be harvested from nearby radio towers or power lines? What circuits would you use? How much would you have to absorb for it to be noticeable by the producers or by other consumers?
I see a lot of stories,…
endolith
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Help with homemade electromagnet
Just for fun, I decided to build what I was hoping would be a relatively powerful electromagnet. I used this copper wire (20 AWG, entire 1 pound spool) and this soft iron core (0.5 in diameter, 6 in length). The total length of the wire is…
x7benihana
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Is it possible to generate light with an antenna?
An antenna (e.g. a dipole) is able to radiate at a certain frequency thanks to the EM field generated by a current provided by a signal generator at such a frequency.
So, for instance:
Voltage source at frequency f (representing an amplifier) +…
Kinka-Byo
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How is it that two electric currents can travel in opposite directions on the same wire, at the same time, without interfering with each other?
An Introduction to Information Theory: Symbols, Signals and Noise, by John R. Pierce, says the following:
While linearity is a truly astonishing property of nature, it is by no means a rare one. All circuits made up of the resistors, capacitors,…
The Pointer
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Why aren't solenoid/electromagnet windings insulated?
This has been bugging me for a long time. Take this video for example.
I have always thought that electricity will take the shortest path. When the electromagnet's windings are uninsulated, it seems that the electricity would flow straight through…
Joel
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In which direction do electric signals flow?
We know that electrons move from the negative to positive terminal, and that holes flow in the conventional direction of current - from the positive to negative terminal.
I've always assumed that this means that electric signals travel in the…
slebetman
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How does the tester screwdriver work?
How does the tester screwdriver work? If I put the tester screwdriver inside the "hot wire" of an electrical socket, it lits up if I press my finger against the metal cap on top of the screwdriver. This happens also if I stand on a surface of…
John Donn
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Why does the thickness of a wire affect resistance?
A teacher explained why by using a highway analogy. The more lanes you have, the faster the cars go through, where the number of lanes obviously represent the wire thickness and the cars represent electrons. Easy enough.
But after a certain point…
user27379
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Why does a simple conductor start to emit EM waves when carrying a signal?
I understand that on circuit board traces with a clock, if the higher harmonics have sufficient power, it results in electromagnetic waves being emitted from the traces which creates EMI. What I don't understand is why this happens in the first…
quantum231
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In a DC motor, is there one commutation point that is optimal in all respects?
This recent question got me thinking about commutation timing, and why advancing it can be desirable. However, I wanted to consider more deeply the underlying phenomena, and I'm pretty sure my understanding is incomplete, so I thought I'd try a new…
Phil Frost
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