Questions tagged [electromagnetism]
The classical theory of electric and magnetic fields, both in the static and dynamic case. It also covers general questions about magnets, electric attraction/repulsion, etc. Distinct from electrical-engineering.
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Dynamic ferrofluid sculptures [duplicate]
http://www.youtube.com/watch?v=UJJuq_pcyIQ
What exactly is going on in the video example? I understand the phenomena occurs because of magnetism but I am trying to figure out the mechanics behind ...
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What is the pressure between two electric dipole sheets of finite extent?
I have recently become curious about modeling the repulsion of everyday objects in contact with one another. By repulsion I mean as you attempt to walk through a wall, the pain in your nose suddenly ...
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Why is the ground state of the ferromagnetic tetrahedron threefold degenerate?
I'm preparing a presentation on Spin-Ice, but something's been bugging me for a while. On the Wikipedia page for Geometrical Frustration, it says the following about easy spins on a tetrahedron with ...
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Navy's new Mach 7 Rail Gun Photo
There have been a few articles about the Navy's new Mach 7 33 Megajoule railgun. As a physics teacher, I have a couple of questions about this, and was hoping for some help.
Is the kinetic energy of ...
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Notation for Sections of Vector Bundles
(Reformulation of part 1 of Electromagnetic Field as a Connection in a Vector Bundle)
I am looking for a good notation for sections of vector bundles that is both invariant and references bundle ...
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What does an atom radiate: a wave packet or a single photon?
What does an atom radiate: a wave packet or a single photon?
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Current from induced emf
If the induced emf in a circuit is negative, and current from this emf is the emf over the resistance, what happens to the negative sign in the induced emf when solving for the current? Surely there's ...
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Creation of the Electromagnetic Spectrum [closed]
After seeing this image:
http://mynasadata.larc.nasa.gov/images/EM_Spectrum3-new.jpg
And reading this:
"The long wavelength limit is the size of the universe itself, while it is thought that the ...
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Utility of displacements potentials in geophysics
In the elasticity theory, you can derive a wave equation from the fundamental equation of motion for an elastic linear homogeneous isotropic medium:
$\rho \partial^2_t \overline{u} = \mu \nabla^2 \...
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Heim Theory and FTL [closed]
Years ago there was some hype around a theory that would supposedly allow for FTL. But I have since heard nothing of this.
Is anything happening with the theory? How would a magnetic field allow us ...
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Alkali atom - photon interaction in zero magnetic field
An alkali atom has a single outer electron that interacts with incoming photons of the right wavelength (for alkalies it's in the visible & IR range). If there is an external magnetic field, the ...
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Maxwell equations: how to know the behavior of charge and current?
In school-level tasks, when (almost) all substances are linear, homogeneous and isotropic, we have $D=\epsilon E$, $H=B/\mu$ and thus Maxwell "in material" equations (1) say how $E$ and $B$ depend on ...
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Would a magnet attract a paperclip indefinitely?
Let's say we have a magnet stuck to a metal bar, suspended above the ground. If I attach a paperclip to the magnet, where is the energy to hold the paperclip coming from (against the force of gravity),...
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