For questions about Electromagnetism - a branch of Physics involving the study of the electromagnetic force, a physical interaction that occurs between electrically charged particles
This tag should be used along with physics tag.
Questions tagged [electromagnetism]
137 questions
9
votes
4 answers
How did early scientists know if a current was changing direction? (AC vs. DC)
How did Faraday, Ampere and Hippolyte Pixii know that electricity 'traveled' at all? Let alone in a certain direction? And that it was reversing direction with certain early generators?
Kurt Hikes
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8
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How did Weyl's 1918 paper; Gravitation and Electricity, influence classical physics?
The main-stream view seems to be that Weyl's 1918 paper Gravitation and Electricity was initially considered a failure for reasons first pointed out by Einstein. But these initial ideas were reapplied to quantum mechanics giving rise to the idea of…
Larry Harson
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5
votes
1 answer
How was it discovered in the 19th century that electric or magnetic forces were not instantaneous?
Marc Lange writes (page 29)
It was known by about the 19th century that any action at a distance involving electric or magnetic forces would be retarded and so undermine not only spatial locality, but also temporal locality.
How was it discovered…
Frank Hubeny
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4
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1 answer
Electromagnetic constants and the speed of light
Was it known before Maxwell's time that the vacuum permitivity was inversely related to the permeability by a factor of $c^2$?
Rascalniikov
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3
votes
1 answer
What were the 3 critical experiments and the argument given by Ampère which helped in determining the magnetic field made by electric current?
In The Feynman Lectures on Physics volume 2, Magnetostatics, section 13-4 Mr. Feynman tells us that there were "three critical experiments and a brilliant theoretical argument given by Ampère" that helped in determining the the magnetic field by a…
Namami Shanker
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2
votes
0 answers
Who introduced concept of capacitance matrix
We know of two ways of representing voltage-charge relations of an assembly of conductors:
$V_j=\sum P_iq_i$ and $Q_j=\sum C_iv_i$
Who introduced these equations for the first time and though one can be modified to other, yet which one of them was…
Kutsit
- 163
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2
votes
1 answer
Origin of Textbook Argument for Displacement Current as Generalization of Ampere's Law
I was wondering where in the literature the standard textbook argument (appearing in Young and Freedman and Purcell and Morin, for example) for displacement current first appears. It seems especially odd to me that Maxwell didn't include it in…
Thomas Smith
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2 answers
How were the values of permeability and permittivity derived?
Do you know how the values were measured and if they where determined by particular conditions/ restraints? They can be put to 1 (or to any values, I suppose); what escapes me is why 1/ε × μ must be equal to c2. Was this an arbitrary choice just to…
user157860
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vote
3 answers
Why make fields have momentum and energy? (or, the importance of conservation laws)
I used to get confused when I first learned the electromagnetic field is said to have a momentum. A few years later, I came across an argument for why 0.999... = 1: When faced with the task of defining what a recurring decimal means, we as a…
user3971
1
vote
1 answer
Who discovered the electric potential?
Wikipedia says that the magnetic vector potential was discovered by Neumann in 1845, by Weber in 1846 and Lord Kelvin in 1847. It does not mention who discovered the electric scalar potential.
Hence my question - who discovered the electric scalar…
Mozibur Ullah
- 3,683
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1
vote
1 answer
Why is the constant of magnetic fields called permeability and that of electric fields called permittivity?
Basically the title, I found it weird that we use two different names for each fields. What were the reasons for doing so, historically speaking?
user12582
1
vote
0 answers
What is a Heaviside rational current element?
This terminology seems to be referred to a notion invented in an old book of Oliver Heaviside [1]. What is it and why the Biot-Savart law is not unique unless it is applied to a Heaviside rational current element as claimed in this paper [2]?…
8cold8hot
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vote
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How and for what purpose did Lorentz come out with his "electron model"?
Who suggested to him the idea that charge wasn't really some excess or defect of "electric fluid", but rather something carried by a particle?
ric.san
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1
vote
2 answers
Who discovered or predicted an electron g factor of circa 2?
I'm writing a physics article with significant historical content, and I'm struggling to find something. Forgetting about the anomalous magnetic dipole moment for a minute, the electron's g factor is approximately 2. This is twice the "classical"…
John Duffield
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0
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1 answer
How on Earth did Ampere come up with Ampere's circuital law?
When I asked for proof of Ampere's circuital law I learned that this law itself is taken as an axiom.
Okay I just need to know how did he come up with such a law? how to confirm that result experimentally?
Is it just a total experimental law?
When…
gogo oka