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

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185 views

Can we explain Huygen's principle taking into account Maxwell's predictions?

Descartes gave the corpuscular model (1637) of light. Corpuscular model was further developed by Issac Newton. Model predicted that if the ray light (on refraction) bends towards the normal then the ...
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0answers
215 views

Vector and scalar potentials of plane wave

Consider a simplest 3D solution of Maxwell's equations: $$\vec B=\vec e_z \cos\left(\frac{2\pi}{\lambda}(ct-x)\right),$$ $$\vec E=\vec e_y\cos\left(\frac{2\pi}{\lambda}(ct-x)\right),$$ and ...
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3answers
127 views

Do electromagnetic waves have endpoints?

When learning about electromagnetic waves at school we never talked about any endpoints as we did with standing waves, so I assumed that light has an endless length, but that doesn't make sense. So my ...
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1answer
64 views

Is it feasible to transfer energy from power stations to communities via photons instead of electrons?

Electrical wires are relatively inefficient in transferring energy--especially when the place of production is quite far from communities. Would it be possible to transfer that energy via photons? I ...
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2answers
164 views

The strange thing about the maximum in Planck's law

I read that it makes a difference whether you calculate $\frac{d \omega}{d \lambda}=0$ or $\frac{d \omega}{d \nu}=0$ in the sense that the maximum energy densit with respect to the wavelength does not ...
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1answer
74 views

How is the orientation of an electromagnetic wave determined?

I was looking up for how polarisers work, I understood mostly everything except the part that explains that the polariser filters everything except light that is in a certain orientation. Here are my ...
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1answer
196 views

Would there be emf induced in our body due to electromagnetic radiations?

The experiments of innovative Faraday and Joseph Henry in USA, conducted around 1830, demonstrated conclusively that electric currents were induced in closed coils when subjected to changing magnetic ...
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2answers
182 views

Why do light disappears the moment we switch off the source (inside the wooden box)?

I am failing to explain why light won't remain inside the wooden box in the following situation. I considered a wooden box closed from all the sides, with a bulb inside it. If we switch on the bulb, ...
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2answers
213 views

Derivation of Lagrangian density for an infinite classical dielectric in interaction with the EM field

I am tasked with reading and reproducing all the steps in J.J. Hopfield's 1958 paper "Theory of the Contribution of Excitons to the Complex Dielectric Constant of Crystals". Embarrassingly I am stuck ...
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3answers
308 views

Does radio use virtual photons?

In radio communication each accelerated electron in the transmitter antenna interacts with an electron in the receiver antenna by exchanging a photon. Is that photon always a virtual photon as ...
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799 views

What is the relation between electromagnetic wave and photon?

At the end of this nice video, she says that electromagnetic wave is a chain reaction of electric and magnetic fields creating each other so the chain of wave moves forward. I wonder where the photon ...
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2answers
204 views

If photons don't interact directly, how can electromagnetic waves interfere?

If photons don't interact directly, how can electromagnetic waves interfere? I know that photons can scatter via higher order mechanisms, but not directly. Does those mechanisms explain the classical ...
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146 views

Do electromagnetic fields gravitate?

It's well known that electromagnetic fields contains energy but do they gravitate ? When we talk about the composition of the universe it's now accepted that the 74 % is dark energy , the 22 % is ...
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1answer
126 views

some questions regarding Doppler shifting versus absorption-emission

I just got in what I thought was a silly exchange where a self-identified physicist states that the difference between "red-shifting" (in the Doppler sense) and the re-emission of light at longer ...
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0answers
237 views

1-dimension radiation problem [closed]

A positive charge $q$ is fired head-on at a distant positive charge $Q$ ( which is held stationary ), with an initial velocity $v_{0}$. It comes in, decelerates to $v=0$, and returns out to ...
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1answer
303 views

Physical Interpretation of Poynting Vector

I'm looking for a physical interpretation of the Poynting Vector. I understand that it should be thought of as an energy flow due to the electromagnetic field, but would I be correct in saying that in ...
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3answers
165 views

What is the Bremsstrahlung or dipole radiation mechanism involved in the emission of radiation by the rotating or moving charge?

A rotating charge such as the electron classically orbiting around the nucleus, will constantly lose energy in form of electromagnetic radiation. I asked my teacher about how this radiation ...
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2answers
247 views

A difference between Plane Wave and Collimated?

Collimation is clearly in reference to ray($\vec{k}_{xy}$ vector) orientation unlike waterfront continuity( $\phi_{xy}$ phase shift) described by plane-wave. Not to say that one is not directly ...
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158 views

Questions about Michelson interferometer

I have been doing experiment on Michelson experiment, but I don't quite understand why white light results in an interferogram with very few fringes, and why are they necessarily Gaussian? I know that ...
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164 views

Do human bodies give off a consistent but unique radiation/electromagnetic/energy signature?

Is there any facet of the energy emitted by a human body that is consistent and unique - like a fingerprint, but a signal that could be detected by a remote device?
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1answer
90 views

Do monochromatic waves carry information?

The answer is negative according to http://www.mathpages.com/home/kmath528/kmath528.htm It should also be remembered that a perfectly monochromatic wave carries no information, and therefore is ...
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3answers
63 views

Can radioactive energies become electromagnetic

I am trying to learn about radioactive energies and wonder if, because these also seem to come under the topic of radiation, can these energies become electromagnetic. I'm pretty much a beginner, so ...
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2answers
344 views

Do accelerated charges radiate or not?

This questions has been asked all over the net (here included) but I can't find a satisfactory answer or discussion. Some say it does not radiate if the acceleration is caused by a uniform gravity ...
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1answer
114 views

Can we draw analogy between em power flow through free space and ac power flow through a transmission line?

Knowing that the free space has a characteristic impedance (which is purely resistive, measured in ohms) I was wondering if I can model the free space as an infinitely long transmission line- ...
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1answer
83 views

Is there a physical reason why the detection pattern of microphones and antennas is a cardioid?

I was wondering if there's an underlying physical reason why detection in microphones and antennas is a cardioid, or if it's just that a cardioid happens to be the mathematical object that best ...
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2answers
364 views

Exciting Surface Plasmon-Polaritons with Grating Coupling

I'm very new the topic of SPPs and have been trying to understand this particular method of exciting surface plasmons using a 1D periodic grating of grooves, with distance $a$ between each groove. If ...
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2answers
400 views

2.45 GHz Microwave oven and Wi-Fi [duplicate]

I noticed that both microwave oven and Wi-Fi use the same frequency band 2.4-2.5 GHz. Yet microwave oven will certainly fry a living being the Wi-Fi has not done yet I suppose. So why is Wi-Fi ...
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1answer
46 views

Is there electromagnetic abrasion / erosion?

When a sensor registers electromagnetic radiation, such as that used for the transmission of communication like light or radio waves, does this radiation "abrade" or "erode" the material of the ...
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70 views

Michelson interferogram white light pattern symmetry

Why is the white light of the interferogram produced by using Michelson Interferometer necessarily symmetric? This is really hard to think.
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1answer
139 views

What is the effect of gravity on gamma rays?

I read an article about a Gamma Ray burst linked to a black hole. How does high gravity fields affect gamma rays?
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31 views

Implications of a phase shift in a 2-ray propagation model

So I am working with a 2-ray (actually it's 8 ray now, but that's merely an extension) wireless signal propagation model. The equation of the component of interest: $ P = ...
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1answer
57 views

Exciting Surface Plasmons using ATR

I'm very new to the topic of surface plasmons and I have been reading about different methods of exciting them. There is one method in which a prism is set up to allow phase matching of an incident ...
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0answers
40 views

Why do (most) metals cause problems in a microwave oven? Which metals (if any) don't? [duplicate]

Most of us have seen microwave ovens with metal racks or shelves, which challenges the common notion that you can't (safely) put metal in a microwave oven. What's going on here? Is it a matter of ...
4
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1answer
179 views

Do higher frequency EM waves travel longer than lower EM frequency waves?

In radio communication, the distance traveling seems to be an important parameter before we choose the frequency band of communication. There is also a path-loss model that describes a distance ...
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1answer
60 views

Slow light and gravitational lensing

It has been proposed that the Sun's gravitational lens be used to observe distant objects, but according to relativity a spacecraft would need to be 550 AU away in order to take advantage of the ...
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1answer
201 views

EM attenuation in free space at different frequencies

Can anyone explain intuitively why electromagnetic radiation (according to the basic path loss equation in communications) experiences more attenuation at higher frequencies? The equation states ...
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2answers
124 views

Is there a differential equation that can represent a circuit with an arbitrary voltage source connected acrorss an antenna?

An RLC circuit with a voltage source can be characterized by the differential equation: $$ LC\;\ddot{I}\left(t\right) + RC\; \dot{I}\left(t\right) + I\left(t\right)-C \;\dot{V}\left(t\right) = 0 $$ ...
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82 views

What is the maximum possible frequency and wavelength?

As a start I assumed Planck angular frequency which is the reciprocal of Planck time as the frequency upper limit, but not so sure. On the other hand, is there a lower limit? Can we consider the ...
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1answer
183 views

Why do dark objects radiate thermal electromagnetic energy faster than light objects?

Kirchhoff's law of thermal radiation says that: For a body of any arbitrary material, emitting and absorbing thermal electromagnetic radiation at every wavelength in thermodynamic equilibrium, ...
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3answers
199 views

What electric field vector should I use for modeling unpolarized light?

Regardless of computational cost, light is a kind of electromagnetic wave, so it can be simulated with Maxwell's equations. If we want to simulate light with Maxwell's equations, we need to express ...
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1answer
78 views

Why are waves, the means, of information transfer over long distances, excluding difusion or contact of info stored in matter

Practical long distance communication, which does not rely on the movement of encoded configurations of matter, from source to destination(odor,books,DNA,floppy disk), always involves waves (EM, ...
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2answers
138 views

How does energy transfer between B and E in an EM standing wave?

I'm trying to understand how an electric field induces a magnetic field and vice versa, its associated energy, as well as relating it to my understanding of waves on a string. Using a standing wave ...
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1answer
185 views

Explanation of photon reflection [duplicate]

What occurs in atomic scale that cause the photon to be reflected? In other words, what is the reason for photons to change its direction and why material can reflect certain wavelengths and absorb ...
4
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1answer
293 views

What is the magnitude of the force on a charged particle due to electromagnetic radiation?

Suppose there is an electromagnetic wave moving forward in the $\mathbf{\hat{k}}$ direction. Its electric/magnetic field components are given by: $$\mathbf{E} = E_0 \sin(kz - \omega t) ...
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1answer
121 views

How light causes increase in temperature

Temperature is the measure of movements of atoms. So if something is said to have high temperature it means that its atoms are moving fast or have high KE energy. There are basically two ways heat ...
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1answer
86 views

X-Ray/Gamma Ray shielding: density versus conductivity

When talking about gamma ray or x-ray propagation in media, we usually talk about the mass attenuation coefficient, and we desire high density materials for shielding. This seems probabilistic: we ...
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1answer
539 views

Definition of the complex wavenumber

My syllabus of electromagnetism defines the complex wavenumber as: $$k = \omega\sqrt{\epsilon\mu}$$ with $\epsilon$ the complex permittivity and $\mu$ the complex permeability. Thus $\epsilon$ and ...
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1answer
89 views

How much photons are needed to erase a complete mountain? [closed]

I've heard that light does change our momentum a little bit which made me think: How much photons are needed to erase a complete mountain? That is to evaporate a complete mountain such as Himalaya for ...
2
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2answers
79 views

Are there any known, non-spectroscopic effects of EM directly on Light?

Photons have no charge. Light is a form of electromagnetic energy. All spectroscopic effects (to my knowledge) are due to changes in electron state, induced either through an interior or exterior EM ...
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2answers
137 views

When light is only considered as a particle, is it still considersed to be oscillating electic and magetic waves?

I have my head around wave-particle duality, however people tend to refer to light as either a wave or a particle in different situations. If I were to consider light as a particle am I still ...