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.
35 questions from the last 30 days
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Would reflections make an electromagnetic wave more penetrating into metals?
First i should clarify how i arrived at this question. I understand that in the case of an EM wave reflected off a higher refractive index surface, the reflected electric field vector changes ...
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EM induction for a circuit deforming in a magnetic field
According to Leibniz integral rule for a moving surface $\partial\Omega(t)$ and boundary $C(t)$ with velocity $\textbf{v}_c(\textbf{r},t)$ for $\textbf{r}$ $\epsilon$ $\partial\Omega(t)$:-
$$\frac{d}{...
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What astrophysical or artificial light sources provide the highest usable irradiance at the Solar Gravitational Lens focal line (∼550–1000 AU)?
The Solar Gravitational Lens (SGL) concentrates light from distant sources into a narrow diffraction pattern along its focal line, starting at ~550 AU. The central PSF contains extremely high ...
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Could there be a circular flux tube in superconductors?
Because of the Meissner effect, magnetic fields can only infiltrate superconductors as discrete flux tubes.
Normally, a flux tube has two ends where magnetic fields enter and exit the superconductor, ...
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Energy radiated (to infinity) by a discharging capacitor [closed]
One of the problems in my assignment is to find the fraction of the initially stored energy that is radiated away to infinity by a capacitor as it discharges.
I am able to find the answer pretty ...
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Hypothetical modification of The Faraday Unipolar Generator Setup for Propulsion [closed]
I am wondering if the following device produces a forward thrust.
Setup explanation
The North (blue) magnetic monopole magnet rod is fixed to the cart as well as the copper spokes (brown) on the ...
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Survey of the ether theory as motivation of Maxwell's equations [migrated]
In all the modern textbooks on electromagnetism that I have seen, Maxwell’s equations are introduced in a rather poorly motivated way, in my opinion. It is often left unexplained how one goes from ...
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Why is graphite a good diamagnet?
Most metals are paramagnetic because metals have a lot of unpaired electrons. While carbon is a nonmetal, because graphite has a lot of unsaturated bonds, those pi electrons can move freely just like ...
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Is it possible to explain how electromagnetic waves propagate through a vacuum solely using classical physics? [closed]
I'm struggling to understand how electromagnetic waves are able to sustain through a vacuum without thinking of them as photons instead of waves.
Am I right in thinking of the situation as the wave ...
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Does Gauss's law need a displacement charge term? [closed]
Maxwell's equations:
Gauss's law
$$\nabla \cdot \mathbf{E}=\frac{\rho}{\varepsilon_0}.\tag{1}$$
Gauss's law for magnetism
$$\nabla \cdot \mathbf{B}=0.\tag{2}$$
Faraday's law of induction
$$\nabla \...
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Why does QED use spinors but Classical Electrodynamics doesn't?
I am curious as to why we find Dirac spinors in QED but when working in CED we can formulate systems using complex scalar fields. For instance, the typical Lagrangian density for a charged particle ...
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Electric field around a wire
Does an electric field exist outside a non-perfect conductor wire with a constant current flowing through it? I think there might be an electric field parallel to the wire because current in the wire ...
- 407
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How does electrohydrodynamic (EHD) propulsion work? [closed]
How does electrohydrodynamic (EHD) propulsion work? In the usual setup there’s a thin emitter wire and a collector electrode. The emitter is held at a high positive voltage, creating positive ions ...
- 407
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Principle of relativity near a charged earth
If earth was electrically charged is it was possible for a person in a train to know that if it is standing still or it is moving by constant velocity?
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Rotation of electric field vector or polarization
Given a circularly polarized light field. I am using complex notation to represent the field,
$$\vec{E}(z=0, t) = \frac{1}{\sqrt2} [ \hat{x} (\cos(\omega t) - i \sin(\omega t)) + \hat{y} (i\cos(\omega ...
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Implementing sources in numerical E&M simulations
I recently started using COMSOL for wave optics simulations and tried to think about how I would implement a numerical simulation to achieve the same results. I quickly realized this scenario was more ...
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How earlier physicists like Maxwell specifically accounted for delay and propagation of changes in fields rather than their instant settlement? [duplicate]
We can see directly from Maxwell`s equations that his equations are for local changes not global which translates to delay and propagation of field changes rather than instant settlements
Question :
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Do photons mediate momentum? [closed]
Question 1: If photons mediate the transfer of electromagnetic forces and most contact we deal with on a day to day basis are electromagnetic forces, is it safe to say that photons mediate momentum?
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