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

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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 ...
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3k views

Force on Earth due to Sun's radiation pressure

I have been asked by my Classical Electrodynamics professor to calculate the force that the Sun exerts in the Earth's surface due to its radiation pressure supposing that all radiation is absorbed and ...
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why dosen't a charged particle radiate energy in circular motion in a uniform magnetic field?

I have studied in my Physics course that one of the drawbacks of Rutherford's atomic model was that when an electron will revolve around the nucleus, it is undergoing acceleration and so it should ...
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86 views

Range of electromagnetic waves

I was reading this article. There is a statement "It is a well-known fact that the telecom towers mounted with antennas in the lower frequency bands can cover far greater areas than those using the ...
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1answer
228 views

Does a magnetic field have gravity?

Re-reading http://physics.stackexchange.com/a/33156/5265; I find myself thinking if light, being EM in the humanly visible spectrum, may possess gravity - does a magnetic field also possess gravity?
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592 views

What is the ion drag mechanism in dielectric heating?

While reading about dielectric heating on Wikipedia, I read about the ion drag mechanism but there wasn't enough information about. I know there is another Phys.SE question talking about the ion drag ...
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1answer
177 views

How does the specific frequency of EM Radiation relate to displacing electrons from their orbits?

I've only a general grasp on how all this works, so it could be I'm asking this poorly or misunderstanding what happens. With that said: The energy of EM radiation is a function of its frequency. ...
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784 views

Radio communication and antennas

I'm trying to understand how an antenna is able to understand, but have a few quesions: I understand that for an antenna to distinguish between 2 (or more) signals, they have to be in different ...
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1answer
411 views

Does $\lambda\nu = c$ hold for all the waves in the universe?

Are all waves in the universe the same as electromagnetic waves? Basically, my question arises from an equation I found in my chemistry textbook: $$\lambda \nu ~=~ c.$$ This states that the ...
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10answers
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Why is light called an 'electromagnetic wave' if it's neither electric nor magnetic?

How can light be called electromagnetic if it doesn't appear to be electric nor magnetic? If I go out to the sunlight, magnets aren't affected (or don't seem to be). And there is no transfer of ...
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1answer
104 views

Does every wavenumber of IR result in a different kind of vibration?

Does every wavenumber of IR result in a different kind of vibration? If that is true, what if a molecule absorb 2 different wavenumbers (which cause different rocking and symmetrical stretching for ...
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239 views

Power due to dipole radiation and time reversal symmetry in classical E&M

The dipole formula for the power loss emitted by a time varying electric dipole is (in natural units) $P = \frac{\dot d_i^2}{6 \pi}$. This is clearly even under time reversal symmetry $T$, but a ...
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144 views

Could we really charge metal plates using microwaves?

While skimming through Dielectric heating, I read that they use microwaves to charge the plates. How do they do that?
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What kind of “camera” and “light” source should I use to detect the intermediate path of a light beam? [closed]

I would like to have an image (in any kind of space), where I see the path of a "light" source. In my understanding the most common, directed source would be a laser pointer. a) Is this correct? If ...
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1answer
751 views

Velocity of electron in electrostatic field. Does radiation matter?

There's a voltage difference of 1000 Volts between two points 2 meters apart. An electron starts at the point of lower potential and is left to travel alone in a straight line until it reaches the ...
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27 views

Why can radio wave travel through walls while imfrared can't? [duplicate]

Possible Duplicate: If both radio waves and gamma rays can travel through walls Does it have anything to do with the materials used to build the wall? What determines if a material can ...
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353 views

Xray compression of secondary in hydrogen bomb

Accounts of the "secret" of the hydrogen bomb describe Xrays from a primary fission explosion reflecting off of the bomb case (occasionally passing through polystyrene foam) and compressing and ...
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3answers
465 views

What if $\gamma$-rays in Electron microscope?

I was referring Electron microscopes and read that the electrons have wavelength way less than that of visible light. But, the question I can't find an answer was that, If gamma radiation has the ...
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2answers
387 views

What's the Significance of Color Changes Between EM-Spectrums?

As everybody knows that Black objects are black because almost all the light that falls on them is absorbed into the material. Little or no light is reflected back toward our eyes, therefore we see ...
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467 views

Width of Gaussian Beam and Refractive Index

I know that in free space, the width of a Gaussian beam can be written as $W=W_0\sqrt{1+(\frac{z}{z_0})^{2}}$. However, I was wondering if it was possible to express this width as a function of ...
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1answer
152 views

1MeV ray hits a band gap of 2eV : trying to understand X-rays

I am trying to understand why radio waves pass though the human body, light does not, but X-rays still pass. In my mind I imagine that radio waves don't supply enough energy and don't excite any ...
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0answers
942 views

What happens with photon when it is slowed down substantially?

In a dispersive media light's velocity can change substantially. Imagine we can slow it down to near 0 what the wave would look like? Frequency of light does not seem to change even at v=0 (at least ...
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6answers
4k views

Why is Light invisible?

Why can't we see light? The thing which makes everything visible is itself invisible. Why is it so?
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381 views

Quantum Mechanics- Antenna emitting electromagnetic radiation

Radio signals are being transmitted in a frequency of $ 8.4 \times 10^9 \text{s}^{-1} $ and being received by an antenna that is capable of receiving power of $ 4 \times 10^{-21} \text{Watt} $ ($ 1 \, ...
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Why there is electromagnetic resistivity $\approx 377\Omega$ in vacuum?

I cant understand that. If there isn't a material that makes it hard to pass, why there is a resistivity $\approx 377\Omega$ in vacuum?
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Does travelling light help us see past versions of an object?

I saw a passage in my son's homework book, constructing a scenario in which a person standing on a planet 65 million light years away from Earth, with an extremely powerful telescope pointed at Earth, ...
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782 views

Where are the harmonics in the radio spectrum?

When I strike a string on my guitar and look at the audio spectrum, I can see the fundamental frequency as a large peak. I can also see the harmonic frequencies as a train of little peaks at ...
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923 views

What is the difference between Quantum teleportation and Radio waves?

Quantum teleportation over 143 kilometres using active feed- forward What is the difference between Quantum teleportation and radio waves?
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Macroscopic chromodynamics

Lately I've been reading about gamma ray lasing phenomena, and I've been wondering about the applications of this. More concretely, the above fantastic question led me to wonder if we could somehow ...
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697 views

Oscillating Dipole: Principle of Receiving and Transmitting Electromagnetic wave?

I am practising to Tfy-0.1064 -elementary-physics-exam and doing this practise -exam here. The problem in Finnish goes like this: "Selosta lyhyesti sähkömagneettisen säteilyn lähettämisen ja ...
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How is wireless communication possible?

Like all my questions, I fear this will be very naive, because my physics background is very limited. Please bear with me. I think of the electromagnetic field as a section of a vector bundle over ...
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Why is there a photon every millimeter on earth coming from a star millions of light years away?

I've been having this confusing thought for so long now it would be amazing if someone could answer me. Imagine this asterisk * . As you see, from the center point, lines go outwards, just like a ...
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3answers
443 views

What makes Poynting's theorem consistent for a charge moving in a static electric field?

Poynting's theorem is given by $$\frac{\partial}{\partial t}\int_{v}Udv + \oint_{A}\vec S\cdot \vec {dA} +\int_{v}\vec E\cdot\vec J dv =0 $$ Where, the total electromagnetic energy inside the ...
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Reflection of Electromagnetic Waves

Visible light - Being an Electromagnetic wave is reflected by glass (take mirror). Would all other waves in the electromagnetic spectrum be reflected in the same way by our simple mirror... For highly ...
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430 views

Origin of Electromagnetic Interactions between Molecules

What is the origin of electromagnetic interaction between molecules? Anyway, it should have some relation with atoms. Also, These electromagnetic interactions are playing a major role in different ...
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What IS reflection?

How does quantum electrodynamics actually explain HOW reflection occurs on a microscopic scale? Note that Feynman's QED lecture series/book is not sufficient, as he only assumes that light DOES ...
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1answer
3k views

Why can glass absorb ultraviolet light?

Please see the following photos. (I cannot post them...) http://i1163.photobucket.com/albums/q554/startanewww/CIMG4545.jpg http://i1163.photobucket.com/albums/q554/startanewww/CIMG4546.jpg From the ...
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5answers
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Why do photons travel?

Photons travel at the speed of light. Is there a known explanation of this phenomenon, and if yes, what is it? Edit: To be clearer, my question is why do photons travel at all. Why do they have a ...
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55 views

Can a combination of two or more x-ray type beams be made to burn tumours at their intersecting focal points inside a body?

A single x-ray or similar type beam can pass through a human body with little or no damage. Has anyone ever tried to use a second beam that is phased to have no harmful reactions with the tissue ...
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271 views

The electron jumps and lets loose photons

Where is the source of the photon. If the photon propagates from within the electrons transit does this point to some sort of field? Does the energy come from a boundary being broken in laymens ...
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Bohr's model of an atom doesn't seem to have overcome the drawback of Rutherford's model

We, as high school students have been taught that-because Bohr's model of an atom assigns specific orbits for electrons-that it is better than Rutherford's model. But what Rutherford failed to explain ...
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666 views

What is the attenuation spectrum of radio waves in pure water?

Here is a plot of microwave attenuation in atmosphere: (source) I'm looking for a similar plot, but for pure water, and a frequency range covering at least 100 MHz to 2 GHz, hopefully more.
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Could you make a bar of metal glow by forcing the charge density on the surface to oscillate?

Since light is just a changing electromagnetic wave through space, could you create light by changing a charge density at a certain frequency?
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42 views

Radiation from farther galaxies

I've read many facts from NASA's webpage.. Sometimes they tell, (for example) "NASA's Chandra X-Ray Observatory discovered this ultra-luminous X-Ray source (about 15 million LY) which shows an ...
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480 views

why is advanced radiation absent?

the Lienard-Wiechert green functions have future and past null cones of radiation. Maxwell equations allow for a continuous range of mixtures between the retarded and advanced components, but we have ...
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572 views

Counting electromagnetic modes in a rectangular cavity and boundary conditions

The electric field in a cubical cavity of side length $L$ with perfectly conducting walls is $E_x = E_1 \cos(n_1 x \pi/L) \sin(n_2 y \pi/L) \sin(n_3 z \pi/L) \sin(\omega t)$ $E_y = E_2 \sin(n_1 x ...
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3answers
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Can light exist in $2+1$ or $1+1$ spacetime dimensions?

Spacetime of special relativity is frequently illustrated with its spatial part reduced to one or two spatial dimension (with light sector or cone, respectively). Taken literally, is it possible for ...
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What is the history behind the factors of 3 in the classification of electromagnetic radiation?

What is the history behind the factors of 3 in the classification of electromagnetic radiation? See e.g. http://en.wikipedia.org/wiki/Radio_spectrum#By_frequency Is this (just) inherited from the ...
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Is it possible to split a single light beam into two beams of opposite circular polarization?

A properly oriented calcite crystal will separate an unpolarized beam into two beams, one vertically polarized and one horizontally polarized. Other polarizers pass just one polarization and absorb ...
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limits on a gauss box of light

Consider a wall defined by $w(x,y,z) = \Theta(x-L)$ which is nonzero in the infinite semi-space of $x \ge L$, as well as a coherent planar standing EM wave travelling in the $z$ plane given by its ...