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

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57 views

How do electromagnetic waves/light travel at the speed of light?

When something reaches the speed of light, then time is said to stop, or at least is perceived to have stopped. The reason is that at that speed, the object become infinitely heavy and requires ...
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2answers
117 views

Would a Faraday Cage protect something from an EMP?

Assume that terrorists manage to detonate an EMP in the middle of the United States. Its range is long enough for the pulse to hit and effectively render useless all unprotected hardware. Let's ...
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1answer
106 views

'Hovering' light rays on the edge of a black hole

According to Prof. Hawking, light rays will 'hover' on the edge of a black hole. If this is true, and the light 'stops' on the edge, how can the electric/magnetic fields which, constitute the light, ...
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87 views

Why is it that fractal antennas can filter out so many frequencies?

As known, fractal antennas are used for example in cell phones. But why is it that so many different kinds of frequencies can be filtered out of the forest of radio waves surrounding us? Is it because ...
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1answer
24 views

Reflection and angle of refraction

Does the angle of refraction depend on the properties of the material if the angle of the incidence is the same for two different materials? Say I shed light on a surface with angle $ \theta $ and ...
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4answers
175 views

What makes the radiation behind slits coherent?

Have a look on the sketch To get such a intensity distribution of light behind a slit we presuppose that all the light that moves on the two lines is coherent; of the same wavelength AND the same ...
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17 views

Electromagnetic Wave Impedance

In a derivation of the transmission and reflection coefficients for light incident at an angle onto a surface where we have a change in refractive indices the proof says that ...
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4answers
2k views

Same photon or different photon?

Consider a typical optical focusing system: A small light source, then a collimating lens, then a focussing lens, and then a detector (e.g. CCD). Assume that source intensity is so low that only one ...
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1answer
124 views

Why can TV broadcasts send such large amounts of data(photorealism) and a PC can't

Firstly I think I am right in saying that TV broadcast are sent via electromagnetic waves which means they are sent via photons, how is that even possible? And then the main questions, how can you ...
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5answers
1k views

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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1answer
60 views

What happens at the point of welding iron?

What is the physics behind welding iron? It is obviously the electricity that causes the two metal parts to fuse but what is the role of the welding rod and why is it said to damage your eyes when you ...
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0answers
28 views

Propagation Of Wave in Rectangular Waveguide

From what I understand, electric and magnetic fields are perpendicular to one another and the direction of wave propagation.The text book states that the direction of wave propagation in the ...
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3answers
652 views

Speed of gravitational waves vs speed of light

I own an educational YouTube channel on physics and astronomy. I am currently working on a gravitational waves video extension to my "How Fast Is It" video book on relativity theory. I have a question ...
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1answer
141 views

Is it possible to create arbitrary shapes of magnetic fields?

I've been reading about Transcranial Magnetic Stimulation (TMS) which can activate neurons using a magnetic field, which got me thinking... what if we can pick and choose exactly which neurons to ...
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1answer
13 views

Methods to ioniz air molecules

What are other alternatives ways to ionize air molecules, except the electric field charging and the use of the so-called corona discharge?
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0answers
36 views

Electromagnetic field produced by a charge?

I guess vibration of a charge particle produces vibrating EM wave and oscillation of a charged particle will produce oscillating EM wave. If charge is only accelerating (speeding up) what will happen ...
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1answer
34 views

What are the experimental results of neutron -neutron scattering?

I'm curious about does a neutron - neutron scattering (if such an experiment was carried out) is an in elastic process or is it accompanied by energy losses. Additional question: What is the energy ...
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4answers
134 views

Why can't the wave model for radiation account for the photoelectric effect?

While I understand the effect of varying wavelength and frequencies on the photoelectric effect, I can't seem to turn my mind around that question... I suspect it has to do with quantas and the non ...
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4answers
512 views

Are EM radiation and EM waves the same thing?

Are EM radiation and EM waves the same thing? I have seen this topics treated separately in many books. It is still not clear to me whether EM radiation and EM waves are synonymous. Is there any ...
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2answers
60 views

What is beyond Gamma Rays and Radiowaves in the Electromagnetic Spectrum?

The electromagnetic spectrum is commonly refered to as consisting of; Radio-waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma Rays - of increasing frequency from left to right. ...
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3answers
45 views

Why are pulsar's radiation beams collimated?

Every picture of a pulsar a see shows a very collimated radiation beam. What is the mechanism generating such a collimation? Note: I am not talking about "relativistic jets". I am talking about ...
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1answer
69 views

Difference between radio waves and other electromagnetic waves?

Yes radio waves have different frequency and wavelength than others but it seems that radio waves are produced by sinusoidal current while other electromagnetic waves do not need need sinusoidal ...
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2answers
114 views

Compton Effect Explanation

Can someone brief me about Compton effect and why does this happen? I searched everywhere read a CERN article too but couldn't understand it.
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1answer
25 views

Laser vs Transmiting antenna

Ok so this will probably will sound stupid to you but please put an effort into elaborating with my train of thought thank you :) For no particular reason this question popped in my head: People ...
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1answer
32 views

Charge affected by EM-pulse. What is the equation of motion?

I'm studying for my test on radiation for Tuesday. I came across this exercise. Thought it looked interesting but now I'm stuck and I can't move forward before I finish this one. Exercise: A ...
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41 views

Frequency of Electromagnetic Radiations/Waves?

"A charge that is accelerated will produce variable electric and magnetic fields. These are electromagnetic waves. If the charge oscillates with a frequency f, then the resulting EM wave will have a ...
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3answers
194 views

How do electromagnetic waves carry energy?

Its said that electromagnetic waves carry energy. Is this because these waves are made up of electric and magnetic fields which can cause changes to the stuff that falls with in their range? Is that ...
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0answers
23 views

The radiation intensity considering dipole, quadrupole and magnetic dipole parts

In page 204 and page 205 of the book "The Classical Theory of Fields" written by Landau and Lifshitz, there is this sentence In averaging the square of the magnetic field, all the cross-products ...
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199 views

What is fundamentally happening that causes light to change its orientation when repeatedly polarized?

When light is passed through two polarizers successively, its intensity and orientation afterwards depends on the angle between the polarizers and the orientation of the most recent polarizer, ...
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1answer
44 views

Do all solid objects emit visible light?

Are there solid objects that do not emit visible light? To my limited and humble knowledge, creating such an object would require us to "only" shift the spectrum of emitted radiation. Is it possible? ...
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3answers
36 views

Frequency of other light in white light [closed]

I have this question in mind because I read that the frequency of light depends only on the source of light. If we consider a source of white light then it emits light of different colours also. Then ...
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0answers
21 views

Huyegns Principle and data transmission

Huygens's principle (The Gist) states that for every object on which light is incident every point on that object acts a light source till light is being incident on it. So is it possible than WiFi ...
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0answers
13 views

What wavelengths of electromagnetic radiation are emitted by the LH2/LOX reaction?

Rocket engines such as the Rocketdyne Rocket System 68 and the Space Shuttle Main Engine use liquid hydrogen and liquid oxygen as propellants. The exhaust from this type of engine is notable in ...
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4answers
8k 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 ...
4
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2answers
166 views

Nature of light in Special Relativity

What is the nature of light in the context of Special Relativity? Is it a photon, or an electromagnetic wave, or something else? I have doubts, because a photon seems to me a quantum mechanical ...
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2answers
39 views

Polarized light from any suface?

From a textbook I read something like this: "When sunlight is reflected from a horizontal surface, the plane of incidence is vertical, and the reflected light contains a preponderance of light that is ...
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6answers
2k views

Light's inverse square law: Does it require a minimum distance from the source?

Does the inverse square law begin to take effect the moment light leaves its source? For example, does light's intensity decrease, i.e. does the area in which the photons might land increase, at a few ...
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0answers
38 views

Plasmon quenching vs plasmon decay. What is the difference?

I'm reading an article "Quenching, Plasmonic, and Radiative Decays in Nanogap Emitting Devices" (pubs.acs.org/journal/apchd5). I don't understand the following: Counterintuitively, we evidence ...
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0answers
39 views

Can a lightning strike cause your car to not run? [migrated]

If lightning strikes a tree in your yard and your car is close by, can this cause your car to not work properly? I had an employee call in stating that lightning struck a tree beside their mobile ...
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1answer
2k views

Why does friction produce heat?

What causes two objects sliding against each other to produce heat? Why don't they generate visible light or something else?
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1answer
44 views

What does it mean physically to set $\exp(ikr)=1$ in the dipole approximation?

In the dipole approximation one sets the $exp(ikr)=1+ik.r+...=1$. ($|<f|exp(ikr)\epsilon.r|i>|^2$). Which makes $k.r=0$. What does it mean physically? Is the plane transverse wave converted to ...
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0answers
62 views

Do gravitational waves have field components like electromagnetic waves?

One way I've been led to understand electromagnetic waves (and I accept that this might be a misconception I have) is that they 'self propagate' through empty space by virtue of the wave consisting of ...
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3answers
103 views

Does an electromagnetic wave necessarily contain many photons? [duplicate]

I've often come across people saying from a quantum physics standpoint that an electromagnetic wave necessarily contains many photons. But doesn't the double-slit experiment conducted one photon ...
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1answer
141 views

What is the strength of the magnetic field required to penetrate an average human body?

Introduction Suppose you are an experimental nanobot researcher trial-ling a new form of medication that involves activation and control of nanobots within the cells of the interior of the human body ...
9
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1answer
147 views

Optical chirality and its possible hierarchy of generalizations

Optical chirality refers to a constant of motion of the electromagnetic field, which measures in some sense how chiral a light field is. Specifically, the pseudoscalar quantity $$ ...
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1answer
125 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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46
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5answers
22k views

Why glass is transparent?

Once I asked this question from my teacher and he replied "because it passes light", "and why it passes light" I asked and he said "because it is transparent". Same question again, Why glass is ...
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2answers
127 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 ...