All Questions
Tagged with electromagnetism waves
789 questions
2
votes
0
answers
44
views
Planar Waveguide — Why Can I Have One Polarization (TE) but not the other?
I am trying to understand the derivation of the mode structure of a symmetric slab waveguide, one in which a dielectric of width $d$ in the $y$-direction (and infinite in the other two directions) is ...
- 1,616
0
votes
1
answer
80
views
Electromagnetic wave equation vs. Maxwell equations (possible solution vs. derivation)
One can take Maxwell equations in an empty space and then derive the (classical) wave equations for both $\vec{E}$ and $\vec{B}$ fields. Examples are given in almost every book or at the Wikipedia (...
- 303
5
votes
1
answer
121
views
Why do longer wavelength EM waves travel further in seawater but the shorter wavelength EM waves travel to greater lengths in fresh water?
I was seeing a video on how the microwaves work in which I found out that radio waves react strongly with the water molecules. I know that EM waves induce currents giving in to conduction losses but I ...
1
vote
2
answers
140
views
How to prove that transmission lines carry equal and opposite currents?
You always hear that, in a two-conductor TEM transmission line, the currents in each conductor are equal and opposite. I'd like to prove this, and I made an attempt (below). We'll assume an asymmetric ...
- 1,113
1
vote
4
answers
235
views
How do electromagnetic waves exist?
So if magnetic fields are made by the shrinking of the different particles in a conductor when there is a current how can magnetic fields be created just by the changing electric fields? In the normal ...
- 307
1
vote
1
answer
92
views
Physical meaning of Fourier transformed Maxwell equations in a vacuum
In RCWA, a semi-analytical approach to the Maxwell equations, one typically starts off with the Maxwell equations in a 3D space whose optical properties are constant in $z$, but periodic in $x$ and $y$...
- 113
0
votes
0
answers
59
views
When the magnitude of the electric charge changes with time
If I place the spherical charge at the origin of the coordinate space and change the magnitude of the point charge over time, the electric field wave from the origin is generated as a spherical wave ...
0
votes
0
answers
32
views
Does passing a current through a perfect conductor cancel out the reflection of the magnetic field?
We are studying reflection in our class. Our teacher said that, for reflection of an electromagnetic wave on a perfect (ideal) conductor, it is the surface current that generates the reflected ...
- 1
24
votes
7
answers
6k
views
Does light travel in a straight line? If so, does this contradict the fact that light is a wave?
It is commonly stated that light travels in a straight line in a homogeneous medium. However, light is also a kind of wave; waves oscillate and they do not travel in a straight line.
Do these two ...
- 359
1
vote
0
answers
85
views
Polarisation and dispersion relation for electromagnetic waves with complex $k$
I'm attempting to answer this past exam question:
The monochromatic plane wave solution for the electric field is given as:
$$
\begin{equation*}
\mathbf{E}(\mathbf{r}, t)=\mathbf{E} \exp [i(\mathbf{k}...
- 11
3
votes
2
answers
294
views
Pebble dropped on a stationary pond with a non-perpendicular angle of impact to help conceptualize the Michelson-Morley experiment
I am trying to better understand the logic behind the famed 1887 Michelson-Morley experiment...and want to comprehend what they EXPECTED to see. As I understand it, the motivation behind this ...
- 188
8
votes
2
answers
422
views
How energy density of EM wave oscillate?
In my textbook, the energy of a photon is given by
Energy = Planck's const * frequency
Since both Planck's const and frequency are constant for a given wave, the energy density should be constant ...
3
votes
2
answers
158
views
Wave Propagation Free Space: Boundary Conditions
The solution of a partial differential equation can only be found if the boundary conditions and the initial conditions are given. Therefore, for every problem statement the boundary conditions are ...
- 287
0
votes
2
answers
148
views
If the current frequency is within the human hearing range, why can't we hear it?
If the current frequency (50 Hz or 60 Hz) falls within the human hearing range (20 Hz to 20 kHz), why can’t we hear it?
0
votes
1
answer
55
views
Example of super-luminal phase velocity and why wave front velocity as opposed to phase/group velocity pertains to causality
As the title suggests, I have heard that phase velocity of a wave traveling in media could exceed the speed of light and become super-luminal, whereas some people claim that group velocity cannot. ...
