Propagating solutions to Maxwell’s equations in classical electromagnetism and real photons in quantum electrodynamics. A superset of thermal-radiation.
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16 views
UV light penetration into silicon
I'm in need of some information about UV (particularly UVA) light's ability to penetrate into silicon. Specifically, I am looking for a relationship between wavelength and penetration depth. Also, if ...
0
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0answers
30 views
Historical aspect of wave theory of light
Huygens thought light as a wave. Wave is a propagation of physical disturbance. We now know that light is electromagnetic field. Electric and magnetic field fluctuates here. What Huygens really ...
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2answers
55 views
How & Why does accelerating charges radiate electromagnetic radiation?
Lets consider it case by case:
Case 1: Charge particle is at rest. It has electric field around it. No problem. That is its property.
Case 2: Charge particle started moving (its accelerating). We ...
4
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3answers
70 views
If light rays obey to the wave equation, why can they be thought as straight lines?
I'm a newbie with physics but I'm wondering how a ray of light can essentially be represented. I have always known that a ray of light proceeds in a straight line until it encounters another object ...
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0answers
42 views
Object $A$ : Object $B$ [closed]
Object $A$ has the ability to send information via some wavelength.
Object $B$ houses object $A$ and has the ability to detect when wavelengths are transmitted.
What is object $B$?
2
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3answers
79 views
Radio antennas that are much shorter than the wavelength
From my limited experience with ham radio when I was a kid, I expect transmitting and receiving antennas to have lengths that are on the same order of magnitude as the wavelength, and in fact I recall ...
28
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4answers
3k views
Why doesn't light kill me?
I was attending my philosophy class and in the middle of student presentations, I found myself mentally wondering off and thinking about light. After a few minutes of trying to piece together how the ...
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0answers
20 views
Does quantum mechanics depend solely on electromagnetic waves? [duplicate]
I am beginning to learn quantum mechanics. Since determining the position of an object involves probing by electromagnetic waves and since i have read a simple derivation of Heisenberg's uncertainty ...
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1answer
25 views
Effectivness of a metallic wall against microwaves propagation
I would like to know how good or bad behave a metallic wall in stopping the propagation of an microwave signal.
To be practical, let's take the example of a GSM relay antenna. If I set up the ...
1
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1answer
73 views
How can we detect X-rays?
I know that X-rays can be detected by various ways, like ionizing of air particles.
Is there a way to detect X-rays,which are photons, by detecting ? Can something absorb the energy of the X-rays and ...
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1answer
41 views
Energy in Electromagnetic Waves
Looking at diagrams of Electromagnetic Waves, it would appear to me that at certain times the waves have zero amplitude, and consequently zero energy. Indeed, substituting in the sinusoidal terms into ...
3
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2answers
72 views
Is light's path a wave?
In a lot of textbooks I see a schematic of light drawn as a squiggly line. I have even heard that some things are too small to be seen because they are smaller than the wavelength of light (and ...
1
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2answers
37 views
MRI's and Electromagnetic Radiation
If the waves in an MRI can go through our body, why is it that light with its magnetic fields gets stopped at our skin?
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0answers
46 views
Mathematical equivalence between Liénard-Wiechert potential and 4-potential in Rindler coordinates
I'm studying the problem of the radiation of an uniformly accelerated point charge:
$$x^{\mu}(\lambda)\to(g^{-1}\sinh g\lambda,0,0,g^{-1}\cosh g\lambda)$$
I found that when a point charge is moving ...
1
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1answer
47 views
Is the de Broglie wavelength of a photon equal to the EM wavelength of the radiation?
Is the de Broglie (matter) wavelength $\lambda=\frac{h}{p}$ of a photon equal to the electromagnetic wavelength of the radiation?
I guess yes, but how come that photons have both a matter wave and an ...
2
votes
1answer
67 views
Difference between electromagnetic radiation (EMR) and Electromagnetic Field?
I'm a freshly graduated electrical engineer. One course that I really struggled with was Field Theory, because it was a lovely assortment of vector calculus and things that were explained to me well ...
3
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2answers
85 views
What happens to the energy not absorbed by a radio?
If a radio tunes to a specific frequency, where does the excess energy go? If one continues to hit the resonant frequency, shouldn't the wire begin to melt at some point from too much energy?
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1answer
52 views
Temperature of glowing materials
As I understand it, Stars emit visible light, OBAFGKMRNS, in the range of $10^3 - 10^4 K$.
Yet materials such as steel emit similar frequencies at much lower temps; red is around 800K.
Why the ...
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1answer
76 views
Uncertainty-principle and the Maxwell formalism of electromagnetic waves
An electromagnetic wave (like a propagating photon) is known to carry it's electric and magnetic field-vectors perpendicular and each depending on the differential change of the other thus "creating" ...
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1answer
27 views
Phasor representation of voltage in frequency domain
In a text on application of electromagnetism in transmission line, there introduces a phasor for the voltage (in frequency domain)
$$\tilde{V}(x) = V^+e^{-i\beta x} + V^-e^{i\beta x.}$$
Here $V^+$ ...
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1answer
54 views
Where is the amplitude of electromagnetic waves in the equation of energy of e/m waves?
Does the amplitude of the photon oscillations always stay constant and if it is not - what are the physical differences between the photon with higher amplitude in comparison to the one with the less ...
1
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1answer
68 views
What properties make a good barrier for microwave (oven) radiation?
Suppose I have plenty of food I want to heat (which will provide load) in the microwave, and one item I don't want to heat. What properties would make a material a a good shield, to reduce or prevent ...
2
votes
2answers
54 views
What materials focus EM radiation in the 2.4GHz range
If glass and similar materials refract visible light effectively, what materials would be best for focusing lower frequencies of EM radiation, if any? If not, what other methods exist for focusing ...
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0answers
45 views
Longitudinal EMAG wave?
I'm reading about optical waveguide analysis, and often come across the terms "transverse electric mode" vs. "transverse magnetic mode". As I unerstand, it means that the electric/magnetic field has ...
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1answer
24 views
Charge gained due to photoelectric effect [closed]
Here I think, one beam will knock out just one electron. So, I am not able to even understand what the question says. Please someone give a hint as to what the question asks...
As source of the ...
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0answers
31 views
Why is Electromagnetic Spectrum Bounded? [closed]
The Electromagnetic Waves having frequencies between $10^{4}Hz$ and $10^{20}Hz$, is called as an electromagnetic spectrum. Why these limits? What is the reason for spectrum to have boundaries? We can ...
2
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0answers
34 views
Difficulty in obtaining the Lorentzian lineshape for natural broadening [migrated]
Not sure if this maybe belongs more in the maths section, but since it comes from a physics problem i'll post here.
when calculating the natural broadening lineshape for a laser we have to take the ...
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1answer
50 views
Fundamentals of electrostatics
Suppose I have a Gold Leaf Electroscope and the leaves are observed to diverge by a certain amount. Now if I send a beam of X-rays and allow it to fall upon the electroscope for a very short period of ...
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3answers
88 views
Why doesn't a stationary electron lose energy by radiating electric field (as per coulomb's law)?
If an electron in a universe constantly generates an electric field why does it not get annihilated ? I am confused because I read that an accelerating charge radiates and loses energy. So, why won't ...
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1answer
45 views
Electromagnetic field to cool a substance?
I saw somewhere that an electromagnetic field would cause a substance to let off thermal energy, ultimately resulting in the substance to cool really quickly.
If this is possible, does the strength ...
4
votes
1answer
102 views
What is the difference between Radiation and Electromagnetic Radiation
Are the two equivalent or is Electromagnetic Radiation a subset of Radiation. I am further confused by the fact that electromagnetic radiation includes both ionizing and non ionizing types of ...
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0answers
55 views
Curie's principle in electromagnetic field theory
I am looking for some explanation and if possible also some references about the applications of Curie's principle in electromagnetic field Theory, precisely in the computation of magnetic (resp. ...
0
votes
2answers
68 views
Bremsstrahlung: why is electron slowed/stopped by the positive nucleus?
I can't understand why the electron is slowed/stopped by the nucleus.
The electron is a negative charge and the nucleus is positive... they should attract each other...
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0answers
47 views
Fourier Transform of ribbon's beam Electric Field
I have a monochromatic ribbon beam with $E(x)e^{i(kz-\omega t)}$ being the electric field's amplitude. I want to show that the lowest order approximation in terms of plane waves is
...
3
votes
1answer
73 views
Can you “fold” EM or light waves? (i.e) long wave that is reflected by mirror in fragments - like in the game “Snake”
So, I was reading about the Casimir effect. Two mirrors facing each other attract to each other in a vacuum. The reason is due to pressure exerted on those mirrors from the multitude of EM waves (like ...
2
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1answer
80 views
What are coherent and incoherent radiation?
What are coherent and incoherent radiation?
I am a mathematician who is self-learning physics. In reading Jackson's electrodynamics and other books, I often hear that radiation is incoherent or ...
2
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3answers
78 views
Producing electricity from all wavelengths of electromagnetic spectrum
Is it possible to produce electricity from all wavelengths of electromagnetic spectrum beside visible light ?Like using gamma rays or x-rays .
2
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0answers
40 views
Analytical solution of two level system driving by a sinusoidal potential beyond rotating wave approximation
A quantum mechanical two-level system driving by a constant sinusoidal external potential is very useful in varies areas of physics. Although the wildly used rotating-wave approximation(RWA) is very ...
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0answers
134 views
Is there any example where electric and magnetic fields are not perpendicular?
Perpendicular electric and magnetic field creates light or other electromagnetic waves. Is it a necessary property to have a perpendicular fields? If not what would happen when the fields are not ...
2
votes
3answers
139 views
If photons can be absorbed by electrons, wouldn't that mean light has a charge? [duplicate]
I am a biochemistry and molecular biology major. If photons can be absorbed by electrons, wouldn't that mean light has a charge? Electrons only attract positive charges. Isn't it?
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1answer
43 views
What happens to the $2\pi$ factor when calculating Raman-shifts in units of wavenumbers?
So from the classical theory, you find a formula for a dipole in a planar electromagnetic wave, where there will be two cosine terms with a frequency (actually angular velocity in $[rad/s]$, as the ...
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0answers
36 views
Time reversed laser
Recently, I read an article on time reversed laser. I don't know why they call it a time reversed. I have a doubt that why they use two laser in the device. And what is an anti-laser?
The device ...
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2answers
191 views
New infrared laser weapon made by the USA - How does it work? [closed]
I have seen this post:
New infrared laser weapon, the Laser Weapons System, could shoot down drones or disable ships: US Navy
You can watch the video as well. that exhibits a laser weapon which can ...
1
vote
1answer
69 views
Why do CD's shatter in a microwave?
Why have I heard that eggs and CD's and DVD's explode when microwaved?
3
votes
4answers
184 views
Are photons deterministic?
I propose the following scenario:
At $t=0$, a photon is emitted from a star. At $t=n$, said photon is received and interpreted by some detector.
My question is whether or not it is accurate to say ...
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1answer
146 views
Photon Absorption and Emission: Conductors v. Semiconductors
I'm having a hard time understanding how photon absorption and emission in metals (conductors) compares to semiconductors. Obviously, in SCs, absorbed photons lead to electron-hole pairs and emitted ...
1
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1answer
31 views
william herschel discovering infrared problem
when william herschel conducted the experiment of separating white light with a prism and measuring the different colors, he put a thermometer past the red color as a control finding it to pick up the ...
1
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3answers
98 views
The rule breaker, emissivity + reflectivity = 1
If emissivity and reflectivity are inversely proportionate, why does glass have a high emissivity of around 0.95-0.97 as well as being very reflective for IR Radiation?
normally it works but not with ...
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2answers
61 views
Special Theory of relativity on electromagnetic waves
Since time slows down and length contracts, when we travel almost at speed of light, if the speed of light (or EM waves) remains same and the wavelength of light remains same, do we measure the ...
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1answer
69 views
What is longitudinal relaxation time and transverse relaxation time？
How do we define the longitudinal relaxation time and transverse relaxation time?
