# Tagged Questions

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### how does graphene affect the refractive index of an optical waveguide?

Could someone help me find data on the electro conductivity of graphene and its effect on the refractive index of an optical waveguide
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### Maxwell's Equations in curved spacetime

I know that we can write Maxwell's equations in the covariant form, and this covariant form can be considered as a generalization of these equations in curved spacetime if we replace ordinary ...
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### A classically trivial quantum field theory of electromagnetism

Presumably there is a field theory of electromagnetism that classically gives trivial equations of motion, but when quantized shows interesting topological phenomena. I am talking about the Lagrangian ...
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### What name would you give to the method of approximating an arbitrary magnet with many smaller dipoles?

Let's say I had an arbitrarily shaped permanent magnet, with total magnetic moment $M_{0}$. Ways to calculate the magnetic field of this magnet include an analytic solution (if one exists), as well ...
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### Reference request for the Aharonov-Bohm effect

I am looking for a good reference to an online source or book, on the magnetic Aharonov-Bohm effect. I have read the appropriate sections from the book by Griffiths and Ballentine, and still haven't ...
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### How does Doppler effect differ between EM -waves in Electrodynamics and Sound -waves?

I have an electrodynamics -course that contains doupler -effect but unfortunately with little explanations. Is it the same thing as the classical doppler effect for example with sound, more here, or ...
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### Impervious nature of solid matter due to quantum degeneracy pressure

On Wikipedia the following statement is made without reference: Freeman Dyson showed that the imperviousness of solid matter is due to quantum degeneracy pressure rather than electrostatic ...
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### What equation describes the electrostatic potential in these circumstances?

I have a solver for Poisson's equation and it works nicely. It uses finite differences. It works in the presence of multiple dielectrics. It also solves the Poisson Boltzmann equation. That is, fixed ...
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### What is electric/magnetic field in a medium?

One method of introducing electric field is based on the measurement of the force acting on moving charged particle. By equating F to qE we determine the electric field E if the electric charge q is ...
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### Electrical machines: electrical and mechanical properties of steels and cast iron

I would like to know a good source of information for the common metals (steels and cast iron). Information that I need are basically the mass density and the electrical conductivity or resistivity. ...
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### What is the magnetic susceptibility of NdFeB?

NdFeB is one of the most popular materials used for making permanent magnets. Yet I could find no link or reference reporting a decent value for the magnetic susceptibility of NdFeB. Magnetic ...
The answer to a previous question suggests that a moving, permanently magnetized material has an effective electric polarization $\vec{v}\times\vec{M}$. This is easy to check in the case of ...