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

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1answer
70 views

Massless particles and the speed of light - New? Theories of existence [on hold]

"The best understanding we have is that it [light] is a disturbance in the electromagnetic fields of charged bodies." http://einstein.stanford.edu/content/relativity/q212.html This is a link to the ...
3
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1answer
59 views

Radiation emission and absorption

Any object can emit and absorb radiation and the power of emission can be represented by the Stefan-Boltzmann law: $$P=A\epsilon\sigma T^4$$ In many texts the net power radiated is the difference ...
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1answer
42 views

If light was able to pass through a wall, would the wall be invisible to the human eye? [on hold]

In addition, to get light to other side of the wall, could it be converted to radio waves and then back to light waves? Edit: My idea was if there was a special material that was painted on both ...
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3answers
4k views

How would an X-ray scanner identify a mirror?

A mirror is normally used to reflect Electromagnetic radiation also known as photons (light) and in airport security or medical facilities, they use X-rays to detect anomalies inside objects or bodies ...
4
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1answer
129 views

Does any lower frequency electromagnetic radiation naturally reach us from the Sun?

I am not sure whether the sun originally emits everything in the electromagnetic spectrum, (whatever the relative strengths of each portion might be), but I do read that many waves, including gamma / ...
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0answers
21 views

States that Wave-length, Pressure and Temperature describe [closed]

I have two doubts : 1 - Can wave-length of light emited by some light-source ( like a black-body ) take arbitrary distance values ( any value in the set of real numbers ) ? 2 - Pressure is the name ...
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0answers
44 views

Mathematical formalism to include wave and particle perspectives of light

Does the exist any mathematical formalism (model) describing the behavior of light and incorporating its particle character (divisibility, quantization) and wave character? (i.e. quantized wave model) ...
3
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3answers
56 views

Unpolarized Light

Suppose I had a ray of unpolarized light, and I was sitting inside the beam and looking at the electric fields oscillating, then , if I am looking at a point how would the oscillations look like? I ...
2
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3answers
184 views

How to understand “accelerating charge radiate” using intuition? [duplicate]

While I know that accelerating charges produces EM radiations (at least in lots of cases), most discussion about this matter only focuses on which kind of situation will emit EM radiations and which ...
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3answers
105 views

Is the Speed of Light an universal spacetime constant, the velocity of electromagnetic waves, or of photons?

This question has been touched tangentially by What's a better phrase than "speed of light" for the universal spacetime speed constant? and Could light travel more slowly than the ...
4
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2answers
448 views

Do x-rays and gamma rays also contain photons like visible light does?

Do x-rays and gamma rays also contain photons like visible light does? If so, then what makes photons of visible light and other waves different? The rest mass of a photon is zero, but as it moves at ...
1
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2answers
41 views

On the shape of magnetic and electric fields in an electromagnetic wave

Electromagnetic waves are generally depicted like this: Where the electric fields and magnetic fields exist in the planes perpendicular to the direction of propagation. I also realize that as the ...
2
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1answer
61 views

Would white light waves act as same as monochromatic waves in double slit experiment?

Would white light waves act as same as monochromatic waves in double slit experiment? If not, what pattern would be seen on the screen?
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1answer
39 views

AM vs FM radio under bridges

I know what the difference between AM (Amplitude Modulation) and FM (Frequency Modulation) radios is. However, I noticed that when I drive under a bridge while listening to a station on AM, it just ...
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1answer
25 views

transfer of electricity through electromagnetic waves

Is it possible to transfer electricity from one place to another without the help of physical wires.
2
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2answers
76 views

Would it be possible to detect nuclear explosion on exoplanet?

How strong would have to be nuclear explosion on exo-planet that orbits some other star for it to be detectable outside of that system. Or it would be impossible due to amount of radiation coming from ...
0
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1answer
55 views

Electromagnetic radiation and black body radiation

I was taught today that the Electromagnetic wave Theory is unable to explain black body radiation. The example that was given to me: When a metal is heated, it emits different frequencies of light as ...
4
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1answer
61 views

Is the body's exposure to an x-ray equal to an airplane trip across the country?

I have heard numerous times when getting x-rays, MRIs, CAT Scans, etc. that each one is equivalent to a cross country airplane trip. Disregarding the different types of radiation as asked in this ...
6
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4answers
708 views

Can an LC oscillator be used to generate visible light?

The LC oscillator is most commonly used to generate radio waves for practical use and the frequency $\omega$ of the LC oscillator equals that of the electromagnetic wave so produced. So, can they in ...
2
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1answer
44 views

Why 21cm line observations is more helpful compared to other radiation?

Why 21cm line observations is more helpful compared to other radiation? Is it only because of its abundance in whole universe or anything else?
5
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3answers
676 views

Why aren't all photons virtual particles even in the “vacuum” of empty space? [duplicate]

I'm thoroughly confused about the nature of electromagnetic radiation. Light is supposed to exhibit both wave and particle characteristics. But does that mean that it is both a wave and a particle or ...
1
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3answers
93 views

Should a Faraday cage block a radio's signal?

Today, I tried creating a very basic Faraday cage by surrounding a radio with two baking trays made out of iron. It didn't seem to affect the radio's signal (AM was being used, not FM). In theory, ...
1
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1answer
42 views

What does the size of an object have to do with it's color?

Stephen Hawking mentions in his book "A Brief History of Time' that quarks are much smaller than the wavelength of visible light so they do not have any color in the normal sense. What exactly does ...
1
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2answers
29 views

optical diffusion (scattering) versus refraction

When an electromagnetic wave meets an interface a part of it is reflected and part of it is refracted (and from the refractive index I can calculate the angles of propagation and the intensities using ...
5
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1answer
75 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 ...
2
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2answers
95 views

Is it possible to have a perfectly black material?

After reading this NASA article about the "blackest material", the following stuck out to me. The tiny gaps between the tubes absorb 99.5 percent of the light that hits them Is it possible to ...
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0answers
16 views

Spectrum calibration from wavelength to energy [eV]

If we have some spectrum on camera after spectrometer, how we plot the spectrum in Energy in eV. Lets say I know which pixel what energy is, how the intensity will have to change as function of E to ...
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0answers
27 views

Confused about SI and CGS Units For E/M Energy

I've been looking at some papers on wakefields of electron beams and I am a little confuded about the units. They do not specify whether or not they are in cgs or SI units. Here is a sample equation: ...
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0answers
18 views

Understanding What A Wakefield Describes?

I am trying to understand the some of the properties of wakefields, namely the energy change. So, as a preface I am interested in primarily the wakefield due to electron beams as they progress through ...
2
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3answers
200 views

Curl of an electromagnetic wave?

I can't understand the concept of the curl of an electromagnetic wave. $$ \nabla \times E = -\frac{\partial \textbf{B}}{\partial t} $$ All of the examples I find show a current through a conductor, ...
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1answer
54 views

Electromagnetic waves in an antenna

There is a few questions that need to be answered in detail but in an easy way... What does it mean to describe the 'plane of polarisation' of electromagnetic waves? Why will some antenna have rods ...
0
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1answer
18 views

How does intensity differ from apparent luminosity in the context of photometry?

Context: photometry in astronomy. Background: The total luminosity $L$ of a star is the energy that radiates in all spatial directions in all wavelengths and is given by the following formula, where ...
0
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1answer
39 views

Electromagnetic waves and group velocity

I have three questions about electromagnetic waves and was wondering whether anybody here could comment on these things: Wikipedia says that there are no longitudinal EM waves, although TM and TE ...
0
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1answer
65 views

Blackbody and standing waves

I'm reading articles about black body radiation and why classical mechanics fails to explain it. My question is: Why do EM waves have to be standing wave in a cavity?
0
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1answer
39 views

Constructive Interference of Electromagnetic Waves

So I was wondering if Electromagnetic wave has the same property of interference as normal waves. I understand that both the electric and magnetic parts of the wave would have to be in the same ...
2
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1answer
51 views

What does it mean for an electromagnetic structure to be resonant?

There are many electromagnetic structures used in microwave engineering and EM devices. For example, patch antennas, metamaterials made from unit cells, etc. When they design structures like patch ...
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1answer
27 views

Increasing Earth's albedo

How much of a difference would it make if every roof, road and vehicle were painted white? This would certainly reduce the urban heat island effect but how much of a difference would it make to total ...
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1answer
22 views

is it possible to change the energy of a waveform like radio wave & turn it into microwave?

In the electromagnetic spectrum, the differences between all waveforms are the "frequency" & energy of the waveform. We are able to modify both of these parameters. So, is it possible to change ...
5
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1answer
56 views

Question on luminosity of a radiant source and its dependence on temperature, and involvement of Doppler Effect

A few days ago, I happened to go through the chapters on Radiation, and Photometry, studying them at quite an elementary level. I studied Wien's displacement law, and the dependence of luminous flux ...
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5answers
4k views

Can the sun cast a shadow?

The sun's light can cast the shadow of another object, but does it ever cast its own shadow?
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1answer
26 views

Quick question about absorption of waves

Suppose a plasma has characteristic frequency $\omega_p$. Since $$n = \sqrt{\left(1-\frac{\omega_p^2}{\omega^2}\right)} $$ For $\omega<\omega_p$, the refractive index will be imaginary - which ...
3
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1answer
44 views

Mathematical Formulation for Accelerating Charges Generating Light?

I haven't been formally taught the fact that accelerating charges generate light, and I have seen the picture of an accelerating charge sending ripples down its field lines, but is there a ...
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4answers
106 views

Why can x-rays pass and not radio waves?

If we stand in an elevator or other metal containers we lose radio signals etc the very same reason for which we cannot see across a block of metal that light cannot penetrate it. However x-rays and ...
0
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1answer
41 views

Electromagnetic wave in a medium with $\sigma \ne 0$ [closed]

I want to prove that the reflectancy of an Electromagnetic wave in a medium with $\sigma$ $\ne$ 0 is: \begin{align*} R_{\|}=R_{\perp}=\frac{(n-1)^2+k^2}{(n+1)^2+k^2} \end{align*} any advice, please? ...
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0answers
26 views

Can temperature affect or change the wavelength or frequency of EMR?

If we were to emit Electro Magnetic Radiation(X-rays for example) to a very hot body such as the sun would we still get X-rays if we had a capturing device at the other end or would the high ...
6
votes
3answers
546 views

How is temperature related to color?

I spent some time studying about temperatures and color of objects. It turns out that as we heat something it turns to red, then yellowish white and if we heat it more it turns to bluish-white. Like ...
3
votes
1answer
65 views

Visualization of electromagnetic field [duplicate]

In the Wikipedia article about electromagnetic radiation one can find the following picture: But shouldn't the E and B field be 90$^\circ$ out of phase? In the depicted way the energy isn't ...
0
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0answers
24 views

Diffraction grating zeroth order intensity

I don't understand how the zeroth order intensity maximum works. The intensity of a transmission diffraction grating is: $$I=I_0\sin^2(β/2)/(β/2)^2\sin^2(Nγ/2)/\sin^2(γ/2)$$ Where $γ =kd\sin(θ)$, ...
0
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1answer
31 views

Signal Induction in a Wire due to Alternating Current

I wanted to make sure I understand induction well enough. Assume we have two wires running parallel to each other. Wire A has a signal of $f(t)$, wire B has a signal of $\hat{f}(t)$. Let's connect a ...
5
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4answers
341 views

Does Light Experience Length Contraction?

Lorentz length contractions states that the length of any moving object gets divided by the Lorentz factor equal to the Lorentz factor for that object (always $\geq 1$), equal to $$ ...