Propagating solutions to Maxwell’s equations in classical electromagnetism and real photons in quantum electrodynamics. A superset of thermal-radiation.

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2answers
189 views

Near Energy In the Null of a Hertzian Dipole

Since $\mathbf E = -∇Φ - ∂\mathbf A/∂t$ one expects an oscillating $\mathbf E$ field even in the null of a Hertzian Dipole unless the two right hand side terms cancel -- which they do in the far field ...
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2answers
913 views

If gravitational waves exist are they technically just another form of light/electromagnetic wave?

I would imagine a gravitational wave would have very similar characteristics to electromagnetic wave, what kind of differences are there?
5
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2answers
575 views

Are there weak force waves?

In the same way as there are electromagnetic and gravitational waves that update the information on their respective field, is there an analogue for the weak and strong forces?
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0answers
44 views

Why does the Microwave disturb the Internet Signal?

I have no back round in physics but was wondering how come every time the microwave is turned on, the internet slows down dramatically?
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3answers
492 views

Is there any effect on mechanical waves by electromagnetic waves (and vise versa)?

Do electromagnetic waves like light and gravitational waves (due to moon for instance) affect on mechanical waves like sound? Can sound change the path of light?
6
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3answers
194 views

Far field diffraction of EM waves: what does the zero frequency signify?

If you have a system of independently radiating electrons/point-charges, the far field distribution of the EM waves can be approximated by the Fraunhoffer diffraction integral, or simply by the ...
4
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4answers
154 views

How do light waves get their size?

An atom or (small) molecule has the size of about 100pm. Elektromagnetic waves range from about 0.1nm up to 1 km. The most common way waves (like light) are caused by 'jumping' electrons to another ...
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0answers
35 views

Is it possible in this Universe to communicate a bit of information with energy that scales sub-linearly with distance?

If we look at all the ways that people do communicate information, they all seem to have a cost "at least linear in distance." For example, communicating over a wire has attenutation, so the energy ...
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0answers
24 views

Can I make a microwave oven case from expanded metal? [on hold]

I want to replace the solid walls of a microwave oven with expanded metal (mesh). From what I have researched if you have a maximum mesh size of 10% of the wavelength, a mesh will act as a faraday ...
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2answers
119 views

What is the least count of the timer clocks used in RADAR?

I was checking out some videos in YouTube regarding the working principle of RADAR. To quote some HOW IT WORKS: World War II Radar (720p), part 1, How does RADAR work? | James May Q&A | Head ...
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3answers
59 views

How to distinguish light rays coming from objects of different material

Motivation: My major focus is on Digital Image Processing (specifically segmentation). Due to external noise, the different parts of an image are not fully quantized. Therefore, various segmentation ...
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2answers
58 views

How do signals go through solid objects? [on hold]

So many types of signals pass, or seem to pass I don't know, through solid objects. How do they do this?
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0answers
21 views

Pound and Rebka experiment and redshift

The difference in the emission frequency from the frequency at the receiver is explained by the shift of this frequency during movement in a changing gravitational potential (see John Rennie's ...
3
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2answers
125 views

Minimum frequency of an electromagnetic wave

Is it possible to create an electromagnetic wave of near zero frequency? An electromagnetic wave carries energy. If we can make the frequency of an EM wave vanishingly small and make it practicality ...
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3answers
3k views

Low frequency electromagnetic waves

Some frequencies of electromagnetic waves are used for transmission of information, like radiowaves, microwaves, light, but some are not.. What about low frequencies? Perhaps low frequencies aren't ...
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1answer
90 views

Why doesn't a uniformly moving particle radiate?

When considering a uniformly moving charged particle, we have the following fields: $$\vec E = \frac{q(1-\beta^2)}{4\pi\epsilon R_a}\vec R$$ $$\vec B = \frac{1}{c^2}\vec u \times \vec E$$ With $\vec ...
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2answers
35 views

Data center copper shielding

I have a data center (5m*5m*3m) wall shielding of copper foils with a width of 1m and thickness of 1mm and overlap of 10cm for each two foil stuck to the walls. I have three questions. 1) Could this ...
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0answers
32 views

How to reduce the intensity of one slit of the double slit experiment [closed]

According to this question Double-Slit Experiment: Effect of Intensity Reduction on Fringes there arises a new question for me. How to reduce in practice the intensity for one slit? Of course it would ...
2
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4answers
3k views

How does the movement of electrons produce radio waves?

I'm mostly wondering about radio frequencies. I understand that voltage is the movement of electrons, and that the antenna acts as a light bulb, emitting at radio frequencies, following the reverse ...
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0answers
55 views

Why are FM radio waves less susuceptible to interference than AM? [duplicate]

When studying modulation of radio waves (or of most electromagnetic waves for that matter) I came across that question. Why are FM waves less susceptible to interference than AM waves? I know that in ...
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0answers
39 views

Electromagnetic field produced by a charge?

I guess vibration of a charge particle produces vibrating EM wave and oscillation of a charged particle will produce oscillating EM wave. If charge is only accelerating (speeding up) what will happen ...
5
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3answers
222 views

What is fundamentally happening that causes light to change its orientation when repeatedly polarized?

When light is passed through two polarizers successively, its intensity and orientation afterwards depends on the angle between the polarizers and the orientation of the most recent polarizer, ...
0
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2answers
2k views

Can electromagnetic fields be used to deconstruct and reconstruct atoms?

I was thinking one day and came up with a theory after reading about how scientists were studying anti-matter by using electro magnetic fields to separate matter from the anti-matter they made. It ...
0
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1answer
165 views

What is the strength of the magnetic field required to penetrate an average human body?

Introduction Suppose you are an experimental nanobot researcher trial-ling a new form of medication that involves activation and control of nanobots within the cells of the interior of the human body ...
2
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2answers
45 views

Does a circularly polarized electromagnetic wave transfer angular momentum from the transmitter to a receiving antennae?

This question is about the rotation of macroscopic objects and looks at the magnetic vector of an electromagnetic wave. As basis for comparison, we consider an induction motor. The stator induces a ...
22
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2answers
7k views

Is it really possible to break the speed of light by flicking your wrist with a laser pointer?

Minutephysics has a popular YouTube video called "How to break the speed of light". In the video it states that if you flick your wrist while pointing a laser that reaches the moon, that the spot of ...
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3answers
11k views

How does the grid on the microwave oven window prevent microwave radiation from coming out?

If I look through the microwave window I can see through, which means visible radiation can get out. We know also that there is a mesh on the microwave window which prevents microwave from coming out. ...
7
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3answers
975 views

Is there a difference between the speed of light and that of a photon?

As in the title I am curious whether there is a difference between the speed of photon and the speed of light, and if there is what is the cause of such a difference?
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7answers
23k views

Why glass is transparent?

Once I asked this question from my teacher and he replied "because it passes light", "and why it passes light" I asked and he said "because it is transparent". Same question again, Why glass is ...
7
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5answers
2k views

Do radio waves travel around the Earth or through it?

Whenever you hear someone illustrating/describing the transmission of radio waves they always make it seem like they'd travel perfectly around the Earth to another distant location. For example, a ...
0
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0answers
14 views

Spontaneous Parametric Down Conversion and the direction of the electric field component

The Spontaneous Parametric Down Conversion process is used to produce a pair of entangled photons. For this photons their electric field components are perfect adjusted by 90°. But the directions are ...
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1answer
59 views

Why do particles moving in circular motion emit em radiation? [duplicate]

For example particles moving in a synchrotron . Which energy of the particle is converted to the energy of the radiation ? What is the relation between this energy and the change in direction of the ...
0
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1answer
33 views

Relation between carrier frequency and data transfer rate?

Is there a relation between the frequency of electromagnetic waves and the rate at which it can carry information? If yes, then what it is and why it is?
0
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2answers
35 views

Electromagnetic waves and their extremes

Why do we have electromagnetic waves only in the wave lengths between 10^2 to 10^-14 metres respectively from radio to gamma waves.? Does any scientific reason exist for that? If it is not so, Does ...
0
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2answers
357 views

Absorbance by using Poynting vector

How should I compute the amount of energy of an EM wave absorbed by a material? Can I just use the divergence of the Poynting vector?
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1answer
46 views

Electromagnetic waves of accelerating charges

Is it true that more accelerating a charge will cause electromagnetic waves of more energy than the energy of the electromagnetic waves cause by lesser accelerated charge ?
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1answer
55 views

Gamma spectroscopy – What is this structure?

What is this strange structure in the gamma spectrum between 450 and 550 keV (below) around the peak at 477 keV? The spectrum seems to rise to a plateau (almost like a small Compton plateau) around ...
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0answers
66 views

Time involved in reflection

Consider light bouncing back and forth between two ideal front surfaced mirrors. How long does the process of reflection (i.e., absorption and re-emission) take?
7
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4answers
254 views

How do electromagnetic waves carry energy?

Its said that electromagnetic waves carry energy. Is this because these waves are made up of electric and magnetic fields which can cause changes to the stuff that falls with in their range? Is that ...
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0answers
30 views

Can accelerated charged particle gain energy from charged medium? [closed]

Suppose a charged particle is moving in a medium. If it is accelerated, it is well known that it radiates energy (even in the vacuum). I was wondering if the charged particle would accelerate through ...
20
votes
1answer
286 views

Should a superconductor act as a perfect mirror?

I have been told that metals are good reflectors because they are good conductors. Since Electric fields in conductors cause the electrons to move until they cancel out the field, there really can't ...
3
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1answer
64 views

A Question on energy of electromagnetic wave

( I initially started to ask, "since according to Quantum-theory of light; the energy of a photon, depends only on the frequency of light-wave (E = h * nu), and no-mention of amplitude. So, does the ...
0
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0answers
46 views

Skin depth and electromagnetic shielding

The term "Skin Depth" refers to the the depth upto which current flows from the surface of an AC-current-carrying conductor. This depth is inversely related to the frequency of the current. Does this ...
3
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1answer
41 views

Antennas and the electromagnetic field

I'm an electrical engineering undergrad and have some questions about radio antennas. We've just covered the electronics and maths of radio theory once the signal has reached the receiver, I'm ...
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0answers
56 views

Why is 2000 grit good enough for a mirror finish?

The mean particles size on a 2000 grit sandpaper is ~ 1 um, which is not that smooth compared with the wavelength of visible light. But usually when I want a mirror finish, 2000 grit will provide a ...
0
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0answers
14 views

How to find the polarization (phase) of the virtual source if image theory is used

Consider a radiating element (actual source) is placed above a ground plane, and if we apply image theory to determine the E-filed, the virtual source will be placed below the ground plane and ground ...
0
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1answer
28 views

WHY are reflections stronger at an angle acording to the Fresnel equation?

When looking straight at a glass surface you can mostly see through it, but if you look at it at an angle it becomes more and more like a mirror surface. This is described by the Fresnel equation, or ...
9
votes
1answer
152 views

Optical chirality and its possible hierarchy of generalizations

Optical chirality refers to a constant of motion of the electromagnetic field, which measures in some sense how chiral a light field is. Specifically, the pseudoscalar quantity $$ C=\frac{\...
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1answer
41 views

Can We “Tune” The Radiation Output Of a Nuclear Device.?

After reading "Project Orion", the 1950's plan to launch a large mass spaceship using small nuclear devices, (and also from common sense), I realise that a lot of nuclear research is classified. The ...
5
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3answers
107 views

Energy of an accelerated charge?

Thought experiment: Let's take a positively charged particle and place it in a vacuum with no electric field. It just sits there. Now, we instantaneously introduce an electric field. The moment ...