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

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Classical absorption of radiation

How does electromagnetic radiation get absorbed by an object (like a black body) in the classical regime? In the classical picture, electromagnetic radiation is produced by the movement of charges, ...
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1answer
27 views

Light / TEM wave in a hollow waveguide

I'm cramming for my EMF exam, and a question came up: Light in free space is an example for a TEM wave, isn't it? (Maybe thats already my mistake) And we learned that in a hollow waveguide only TE ...
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80 views

“X-rays”, “gamma rays”, “sun rays”… But electromagnetic waves are NOT rays and DO NOT consist of rays?

In a separate question I'm struggling to figure out the nature of EM waves. But it's a vast topic and I'm trying to narrow it down to small specific questions. It turns out that all electromagnetic ...
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1answer
78 views

Is the wobbly rope depiction of a radio wave inherently wrong? And how do vectors of parallel waves align with each other?

I don't have a scientific education, yet I'm scientifically curious. Among other things, I'm struggling to understand the nature of electromagnetic waves. What I have recently realized is that the ...
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1answer
30 views

Determining path of light through a nanolens

In the case of light passing through stacked liquids, we can use a ray approximation of the path of light to determine the path taken through each layer of liquid using Snell's law. From all the ...
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1answer
63 views

Is it possible for the light (photons) to turns into normal electromagnetic signal?

I want a theoretical opinion about this question: The relativistic Doppler Shift equation for the light is $$\frac{f_s}{f_o}=\sqrt{\frac{1+\beta}{1-\beta}}$$ where $\beta=v/c$ is the velocity of the ...
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1answer
75 views

How can radiation be a transverse wave? Does light really resemble a rope? How can a 3D field be a medium for non-spatial 1D waves? Need mental model

I understand longitudinal waves. For example, I've got a clear mental modal of air waves: a slice of air becomes overcompressed, then the slice next to it becomes overcompressed and the first slice ...
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69 views

The logarithmic decay of WIFI

I have been told that Wi-Fi, LTE etc signal strength fall of as $$\propto \frac1{\log(r)}$$ where $r$ is the distance. I am wondering why this is. I better explain what I mean with this question. ...
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1answer
41 views

How can I measure the ability of sunglasses to block UV radiation?

The most important function of sunglasses is to protect the eye against UV radiation. When they don't adequately filter ultraviolet (UV) light, it may even be worse to wear them than not to, because ...
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0answers
37 views

How many different ways of generating electromagnetic radiation you know? [closed]

I am interested in a list that also takes into account the causes at the atomic level. For example, radio waves from antennas are a periodic electromagnetic radiation. At the atomic level, the cause ...
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1answer
24 views

How can I find the radiance over a finite range of wavelengths using Planck's Law?

I'm working on a small programming project involving Planck's Law, and I keep getting errors. I'm fairly certain this is due to a misunderstanding of physics on my behalf. Basically, I am trying to ...
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0answers
21 views

Spectrum of constant accelerated particle

Suppose we accelerate a proton with a constant Potential U . The particle is accelerated from a zero initial kinetic energy to a maximum kinetic energy of $E_{c,f}$ within a distance L . From ...
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21 views

X-ray characteristic radiation

A high speed electron knocks an orbital electron in the atom. This collision creates a vacancy that is filled by an electron from a higher energy level. My question is, what happen with both electrons ...
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2answers
46 views

A plane electromagnetic wave - phase change - amplitude

A plane electromagnetic wave has the shape: $\vec{E}(\vec{r},t)=E_0\cdot cos(\vec{k}\vec{r}-\omega t)\cdot \vec{e}_y$ $\vec{B}(\vec{r},t)=(B_1\cdot cos(\vec{k}\vec{r}-\omega t)+B_2\cdot ...
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0answers
15 views

What is the equation to calculate the strength and radius of an electromagnetic pulse?

With this interesting answer on the blast force of a uniformly charged electron sphere, came another interesting question. What would be the strength and blast radius of an EMP launched from such a ...
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1answer
37 views

Can you use infra-red goggles (or similar principle) to see through mist and fog?

As per title really... fog is obviously quite opaque to visible light yet transparent to radio waves. What is the range of frequencies at which fog is opaque, and is either end of this range at a ...
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0answers
27 views

How to achieve transmission only at normal incidence?

Is there any material that only transmits normally incident radiation and reflects it when it's incident at any other angle? Or any way to achieve such an effect? For example, a mirror that if you ...
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1answer
27 views

Two questions about the nature of induced emf

I have two questions about magnetic induction (I am in university level introductory E and M so maybe my questions will be answered over the next few years): In the linear generator (shown below), I ...
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3answers
39 views

Antenna direction

I have a router with a wifi antenna that can be turned in any angle. I wonder what difference does the direction of the antenna make to the electromagnetic signals propagation? Where is the signal ...
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1answer
38 views

What is the frequency of each of the moving electrons in a DC current?

I know that the DC current has 0 frequency. But what about each individual moving electron that makes up that DC current? Of course there has to be a frequency as all moving electrons are vibrating at ...
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3answers
798 views

How does the heat of Sun come on Earth when there is no medium?

Sun is the most important source for life on Earth which gives sunlight and heat on Earth. But I was wondering like how does the heat of Sun come on Earth when there is no medium out there in space?
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1answer
30 views

Gaussian beam shape

In this diagram of a Gaussian beam, why does the radius vary with z position? Is it assumed that a Gaussian beam is always being focus by a lense? Why can the beam not go any smaller than $w_0$ and ...
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Energy emitted by a nonuniformly accelerated charge

The question I have is like this: A charged particle of mass m and charge q is accelerated in a straight line along a potential gradient of x V/m from initial velocity u to to final velocity v (u and ...
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4answers
105 views

Has cosmic microwave background kept a constant frequency?

Has the frequency of CMBR changed at all since the beginning of the universe? Has it always had a microwave frequency or has the frequency increased/decreased over time or is the change due to factors ...
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2answers
84 views

Wave number of $\mathbf{E}$ field

If I have an $\mathbf{E}$ field: $$ \mathbf{E}_1 = x E_0 e^{-j(y-z) } $$ I think I can find its wave vector direction by finding the $\mathbf{H}$ field and then solving for the Poynting vector ...
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1answer
25 views

What wavelength of light is the term 'focal length' defined against? [closed]

Because different wavelengths of light are bent differently in a medium, the focal length ought to be different for each of them (which is why white light splits up into a rainbow). If I have a "25 mm ...
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1answer
51 views

Can electromagnetic radiation be half-wave rectified in free space? [closed]

Electric field strength vs propagation direction of electromagnetic radiation(Wave Profile Comparison)
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1answer
54 views

does photon travels in a helical path in an optical vortex?

The wave front of the optical vortex beam is helical. Does it mean that the photon travels in a helical path? When the optical vortex beam is focused on a screen, an annular ring with dark center is ...
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1answer
50 views

If EM waves are not physical, positional waves (on a X,Y,Z axis), why does interference pattern appear positional?

I have read that EM waves propagate in straight lines: https://van.physics.illinois.edu/qa/listing.php?id=17699 Wherein the only the electric (E) and magnetic (B) fields to change (or oscillate) at ...
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1answer
25 views

How does light filtration work?

How exactly do certain types of glass filter out light within specific frequencies/wavelengths? I'm wondering because I read somewhere that certain types of windows filter out certain parts of the ...
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2answers
38 views

What is the least count of the timer clocks used in RADAR?

I was checking out some videos in YouTube regarding the working principle of RADAR. To quote some HOW IT WORKS: World War II Radar (720p), part 1, How does RADAR work? | James May Q&A | Head ...
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0answers
24 views

visualization of Radar waves [closed]

I'm fairly interested in broadening my understanding of Radar waves due to my interest in modern air warfare in which radars play a very central role. How would radar waves appear visually if they ...
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0answers
17 views

Is there a name for the squared refractive index?

In studying wave propagation through multilayers, the squared refractive index $n^2$ is a more pertinent parameter than $n$ itself. Is there a received name for $n^2$? Of course, as long as there is ...
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3answers
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Why doesn't the motion of a car affect the frequency of radio stations?

When we go in a car and tune to an FM radio station, why doesn't our motion disturb the frequency? Like the Doppler effect?
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1answer
31 views

When align the neutron's magnetic dipole moment, does moving neutron radiates?

Was performed an experiment in the past, where neutrons pass a magnetic field and their magnetic dipole moment get aligned? Was measured an electromagnetic radiation during the experiment?
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42 views

Photograph of Light as Wave and Particle [duplicate]

what is this? actually its the first photo of light as wave and a particle. The bottom "slice" of the image shows the particles, while the top image shows light as a wave. i have questions 1.how ...
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1answer
58 views

Explanation of Interference of Electromagnetic Waves

There is a question on a test which goes like this: "Given two electromagnetic waves, one of wavelength 6.0 X 10-7 m and the other of wavelength 7.0 X 10-7 m, travelling in space. When the two ...
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1answer
81 views

Do EM waves need a medium to propagate? [duplicate]

The official theorie says that they don't need a medium, it states that: EM waves are a disturbance in the field First of all, what field?? An electromagnetic one ? I mean, I consider that field as ...
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0answers
14 views

Looking for full equation for radar cross section of corner reflector

There's a well-known formula for the RCS of a corner reflector (aka corner cube), to wit $ \sigma \varpropto \frac{L^4}{\lambda^2} $ . I've found several sources which cheerfully say "...valid for $ ...
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3answers
134 views

What can change a photon's frequency?

I found this question: Is it possible to apply force to a light particle? As it states, gravity can change the frequency of light by changing its momentum. My question regards other phenomena that ...
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0answers
19 views

How do you calculate the magnitude of the light waves emitted from an LED?

Question is in the title. My goal is to see if this is enough to make an interferometer using a surface-mount photodetector.
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4answers
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35
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4answers
4k views

Do rainbows have ultraviolet bands and infrared bands?

We have seen that rainbows looks so colorful as we are only able to see only the visible light. But Do they also have ultraviolet bands and infra-red bands, that we are unable to see? I know someone ...
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0answers
21 views

Are the EM waves that result from each of these processes distinguishable? Phase of light upon emission

In case 1, you have a single source of light that you pass through a diagonally oriented linear polarizer and then a half waveplate, such that the horizontal and vertical components become $\pi$ out ...
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0answers
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My microwave oven disrupts my bluetooth connection even when I'm 12ft away. Should I be worried? [duplicate]

I often wear bluetooth headphones that connect to my mobile phone. I work on my laptop in my dining room approx. 12ft away from the microwave oven and my mobile phone is usually in my pocket; ...
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1answer
33 views

ionising atom(s) with gamma rays

if a gamma ray hits an electron and transfers energy, does it hit that electron (ionising the atom), transfer all its energy and stop or does it pass through multiple electrons, transferring a portion ...
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2answers
69 views

Would passing horizontally polarized light through a varying width vertical slit allow you to measure the positional (x) amplitude of light? [duplicate]

I have found closely related questions on StackExchange, but (surprisingly) not this exact question. Seems some answers say individual photons do not have amplitude, only when traveling with other ...
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1answer
52 views

How to create a vaccum tube & produce electron beam

I know that when an anode & cathode are placed inside a vaccum tube, electrons are emmited from cathode and goes towards anode. So, How to produce such a high voltage?, How to create such a ...
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1answer
51 views

If EM waves are made of oscillating electric and magnetic fields, how come photons have no charge?

I just recently learned that electromagnetic waves are made of oscillating electric and magnetic fields, and I have a question. In the standard model, photons are described as having zero charge, and ...
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1answer
34 views

Plane Mirror as the Screen in Young's experient

If I place a plane mirror instead of the screen in the Young's double slit experiment, what will I see? Will the bands appear on the mirror face?