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

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Linearly accelerated charge experiment feasibility

Wikipedia states: Though maybe it is surprising, there is no experiment that measures directly if an uniformly accelerated charge radiates in an inertial frame. Classic electromagnetic theory says ...
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1answer
35 views

Does the re-arrangement of chemical bonds happens due to electromagnetic interactions?

The question is of some interest because the storage of energy in a recharable battery is not caused by gravitational (potential) nor by kinetic energy. From this question Why is current the same in ...
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2answers
58 views

Gravitational waves vs. electromagnetic for telecommunications

Assuming it would be possible, what would be the advantages/disadvantages of manipulating gravitational waves for telecommunications versus using electromagnetic?
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2answers
47 views

Why is the energy expressed in an electron orbital change of state electromagnetic (photon)? [on hold]

As I understand it, Schrodinger's wave equation predicts the allowable energy states an electron can have under the electromagnetic forces of a given nucleus (and I assume other 'orbital' electrons). ...
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2answers
1k views

Could Google scan books without opening them? [on hold]

A few years ago, I read an article about a proposal Google put forward, as part of its paper-to-digital media project, which had the advantage of greatly speeding up the process of scanning text. The ...
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0answers
25 views

Black Hole Scattering of Low-Frequency Light

What is the far-field interference pattern for low-frequency (i.e., the wavelength is much larger than the Schwarzschild radius) electromagnetic plane wave radiation about a point mass? I envision a ...
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1answer
33 views

Wave nature of light [closed]

I'm currently working on a project to demonstrate the wave nature of light. Now, my question in specific is: How could the phenomenon of interference be used to MATHEMATICALLY explain the wave nature ...
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1answer
71 views

How does a photon 'know' when to reflect in case of refraction? [closed]

In thin-film interference and in glass fibers refraction is involved. Depending on the angle of which a light ray enters the material it will be reflected or transmitted. The refraction depends on the ...
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1answer
44 views

What is absorption rate of WiFi and Bluetooth RF in water? [closed]

Specifically, frequencies 5.75GHz and 2.4-2.485GHz. I want to place a hermetically sealed circuit at the bottom of a gold fish bowl, and want to know if the water will significantly attenuate WiFi or ...
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2answers
1k views

The speed of light upon reflection [duplicate]

(NOTE: I am an 8th grader, so I may not be capable of perfectly elaborating my point by scientific measures. Also, English is not my first language) I have read that the speed of light is constant, ...
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5answers
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How many photons are needed to make a light wave?

What is the smallest number of photons needed to make a "light wave"? In other words, how many (coherent?) photons start to exhibit classical behavior? For example, how many photons are needed to get ...
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6answers
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Why does matter/antimatter only produce gamma rays?

According to wikipedia, all antimatter annihilation produces gamma rays (along with potentially other elements). Why specifically Gamma rays? Why not electromagnetic waves of other wavelength?
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1answer
41 views

What is the quantum (e.g. Photon) phenomena that represents the EM wave impedance?

The EM wave impedance of free space is said to be ~377 ohms and represents the ratio of Electric field strength (E) to magnetic field strength (H). So that: $$ \frac{E}{H} = ~377 \,\Omega $$ When ...
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1answer
46 views

Change in Speed of Light [duplicate]

Whenever light enters from air to glass its speed decreases but when it cross the glass and again come in air its speed increases. What is the reason behind this property? What is slowing it and what ...
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1answer
39 views

Is the electromagnetic wave produced by a linearly accelerating charge sinusoidal?

I have just learnt that accelerating charges produce electromagnetic radiation. When a charge initially at rest suddenly accelerates, the transition between the new and old elctric field lines ...
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1answer
55 views

Cardboard allows AM/FM waves but NOT light - Why?

I am going through Electromagnetic waves. In footnote, the author was giving illustration on transparency of materials. Was going through some references here as well as in Google. Many people ...
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2answers
71 views

Properties of electromagnetic radiations with respect to wavelength [closed]

If two electromagnetic waves have same wavelength, does that implies both of them have same frequency and intensity?
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4answers
2k views

To what extent can speed of light be reduced? [duplicate]

Light slows down upon entering different transparent objects, and the ratio is taken as refractive index of the object. If light can be slowed down, then is there a limit up to which it can be slowed ...
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0answers
52 views

How to correctly calculate the colour of the sky?

It is well-known that the sky is blue due to Rayleigh-scattering. What bothers me though is the question how to actually calculate the spectrum of the scattered sunlight. Yes, use one of the ...
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0answers
72 views

In a moving light clock, does the velocity of the clock add to the velocity of the light?

Currently going through the class Space, Time and Einstein from worldscienceu. On module Time in Motion an example is given of 2 light clocks, one moving and one stationary. The point is made that ...
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1answer
27 views

Why do Very high frequency (VHF) radio waves have limited range?

Why do ultra high frequency radio waves (ex: 2.4GHz or 5GHz) have limited range ?Is it to do with absorption ?If so how do these waves get absorbed when the ELF waves are not ,and on the other side ...
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1answer
25 views

Transmission line model proof?

Why 2 distributed lines is represented with series inductor and resistor along with parallel capacitor and resistor? What is the motivation for that? In circuit theory I Knew the assumptions to ...
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1answer
14 views

Intensity of EMR and time dependence

I imagine an electromagnetic wave as the propagation of electric and magnetic fields. Consequently the amplitude of the field vectors are time-dependent. I also know that the intensity is ...
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2answers
36 views

Can an electromagnetic wave be split into multiple longer wavelength waves?

Is there any way to convert short wavelength (visible light/near infrared) electromagnetic waves into multiple long wavelength waves (microwave) of near equal total energy? Heating a blackbody with ...
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1answer
279 views

Why do planets not radiate EM waves in their orbits?

Despite being overall near-netural, I would expect the individual electrons and proton to radiate long EM waves as we accelerate around the Sun or rotate around our poles. Is the acceleration so small ...
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0answers
25 views

Why is the phase change of a reflected light ray one quarter wavelength?

Suppose a photon beam impinges on a half-silvered plate such that half of the photons are reflected and other half are transmitted. If $\lvert A\rangle$ is the state vector of the incident ray, and $\...
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1answer
27 views

Can antennas work with high frequency EM waves?

Antennas usually work with FM waves, and AM waves, which mostly used in telecommunications. Information is transferred on FM, and AM waves by a transmitter transmitting information on these EM waves. ...
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1answer
13 views

How would I construct an EMI shield for low frequency EMI?

By low frequency, I mean 30-100 Hz. Would a Faraday cage or something like it be feasible? I am trying to shield two separate locations on a high voltage cable.
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2answers
68 views

Why do smartphones need towers to send messages? [closed]

Why do smartphones need towers to send messages? Why can't they send messages directly to each other?
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1answer
40 views

Is it possible to create a Faraday cage transparent to only violet/blue light from natural white light?

If a Faraday cage’s hole size determines the wavelength of light which can penetrate it then I would imagine this would be possible.
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1answer
35 views

Can photons excert radiation pressure after negative interference? [closed]

Motivation: understanding the EMDrive In the context of speculating how the EMDrive radio frequency resonant cavity thruster may work, in case it turns out to do that, there is one point that really ...
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1answer
51 views

Name of electric force

during a lab experiment, i noticed that a metal ball has a much harder time rolling on metal rails when their is a current passing through it and the rails. I was wondering why and if there was a name ...
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4answers
124 views

How can fields interaction give rise to particles?

We say light a matter-wave, meaning along with its wave property it shows particle nature. But how can fields interaction (electric and magnetic) give rise to particles (photon)? I wish someone could ...
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2answers
77 views

Can we see/detect things which don't have electrons

Whenever we sees a thing the process happening at atomic level is the electrons of that stuff absorbs the energy from packets and goes to higher state and then comes to ground state and emits ...
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7answers
2k views

Prove that an electron in a hydrogen atom doesn't emit radiation [duplicate]

According to electrodynamics, accelerating charged particles emit electromagnetic radiation. I'm asking myself if the electron in an hydrogen atom emits such radiation. In How can one describe ...
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51 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
538 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?
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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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2answers
73 views

How do signals go through solid objects? [closed]

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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3answers
65 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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3answers
149 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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1answer
91 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
37 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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62 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
15 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 ...
2
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2answers
54 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 ...
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1answer
64 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 ...
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1answer
35 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?
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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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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?