All Questions
Tagged with speed-of-light electromagnetism
162
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Is it possible to get an electromagnetic wave equation if the speed of light were infinite?
In an old question: How would night sky look like if the speed of light was infinite? the best answer was voted down to negative credits.
I cannot understand why. From Maxwell's equations, we derive ...
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1
answer
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Inconvenience of speed of light in optic fiber
As far as I'm concerned, optic fiber is great in order to transport information quickly using light. Since light needs to undergo total internal reflection every single time it hits the walls of the ...
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Non-homogenous Helmholtz equation in 3+1D: Green's function and solution
I've been reading Jackson's Chapter 8.10 and trying to find the Green's function for a non-homogenous Helmholtz equation. The problem is in cylindrical coordinates.
I first made a Fourier transform to ...
1
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2
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On the (variable?) nature of $\epsilon_0$ and $\mu_0$
In electromagnetism, the electric displacement field D represents the distribution of electric charges in a given medium resulting from the presence of an electric field E. Its relation to ...
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Could relativity be consistent if there are multiple light-like fields with different invariant speeds?
My understanding of real physical theory of electromagnetism goes like this:
The Maxwell equations can be used to derive the speed of light;
$$\nabla\cdot\textbf{E}=0$$
$$\nabla\cdot\textbf{B}=0$$
$$\...
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3
votes
1
answer
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Can the refractive index of a medium be negative?(<0)
Recently I was asked in a test what would happen if the refractive index of a medium was negative. Is it possible really? The refractive index is the ratio of the speed of light in a vacuum and ...
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1
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Proof of speed of light from Maxwell's equations in integral form
Is it possible to prove that
$$\displaystyle c = \frac 1 {\sqrt{\epsilon_0 \mu_0}}$$
using Maxwell's equation in integral form?
Recently, I saw this kind of proof by Professor Walter Lewin in one of ...
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Relativistic Doppler Shift vs Classical Doppler Shift Contradiction
In classical/Newtonian mechanics, the doppler shift (for light) can be expressed as:
$$ \frac{f_r-f_s}{f_s}=\frac{1+\beta}{1-\beta}-1 $$
In relativity the doppler shift can be expressed as:
$$ \frac{...
2
votes
1
answer
84
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Do light's electric and magnetic components oscillate in physical space?
I have heard that light is a transverse wave which is necessary for effects like polarisation, but I am unsure of what exactly this means. Is this saying that light's electric and magnetic components ...
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Moving at the same speed relative to electrons thus no current but seeing light being generated?
Imagine a situation where I'm moving at the same velocity as the electrons in a conducting wire. In this scenario, from my frame of reference, the electrons appear to be stationary and thus there is ...
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5
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Does electric field have a speed itself?
If we bring a charge into the system, it produces electric field around it. I wonder if the propagation of this electric field has the same speed as light. Note that I don't mean electromagnetic field....
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On the electromagnetic wave equation
Solving the Maxwell equations leads us to,
$$\nabla^{2} \vec{E}-\frac{1}{c^{2}}\frac{\partial^2 \vec{E}}{\partial t^2}=0$$
And
$$\nabla^{2} \vec{B}-\frac{1}{c^{2}}\frac{\partial^2 \vec{B}}{\partial t^...
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Speed of EM Waves
We know that for electromagnetic waves, according to Maxwell's Theory
$$v=\frac{1}{\sqrt{\mu\epsilon}}$$
Now consider an opaque object like say Gold. It has a particular value of permittivity and ...
0
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1
answer
116
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Why does redshift happen?
If an object B does NOT move away from us, doesn't matter whether it's 10 km or 5,000,000 km away from us, I think redshift wouldn't happen.
Now, if the object is moving away from us, it's said that ...
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Why is the phase velocity in a transmission line not affected by its geometry?
When deriving the speed of light in vacuum, one usually starts from Maxwell's equations, does some calculus and finds a wave solution with the phase velocity $c = 1/\sqrt{\mu_0 \varepsilon_0}$. This ...
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