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

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49 views

Is the photoelectric effect 'Ionising Radiation'?

According to the definition on Wikipedia, ionising radiation is radiation which has sufficient energy to remove an electron from an atom. So a high energy gamma ray is definitely ionising, but visible ...
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2answers
52 views

Description of a photon and quanta

Could someone please help to clarify the difference between a photon and a quanta? Below is my current understanding - please correct me if I am wrong. A photon - is a 'wave particle' of 'light'. I ...
15
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1answer
914 views

Why is everything not transparent? [duplicate]

There is a related question on this site here: Why glass is transparent? Which explains that glass is transparent because the atoms in glass have very large energy differences between energy levels ...
2
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2answers
66 views

How can 2 EM waves null each other at a point but continue to propagate?

how can 2 EM waves (travelling in opposite directions) null each other at a point in space but continue to propagate beyond the point in space where they interact to null each other?
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0answers
23 views

Dependence of Noise Tolerance of waves

Electromagnetic waves are used for transmission of any message. And different kinds of waves have different noise-tolerance. If my guess is right then the noise tolerance is a property of wave which ...
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0answers
51 views

Why call it a particle and not a wave pulse?

My physics textbook says that photoelectric emission provides conclusive evidence for the particle theory of light. Apparently, since photoelectric emission only works at certain frequencies, we can ...
0
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1answer
90 views

Maximum wavelength of a photon/electromagnetic radiation?

This asked; What is the minimum wavelength of electromagnetic radiation? And also this; What is the maximum possible frequency and wavelength? The second question is contradictory; maximum ...
8
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4answers
144 views

Why do the edges of glass blocks create a shadow?

I have always observed that the shadow of glass blocks becomes darker as the glass is moved away from the surface where the shadow falls. And I know this is because refracted light rays from the glass ...
0
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2answers
286 views

What is the amplitude of the electric field in a laser?

I'm looking for reliable informations about the amplitude (not the intensity), in volt/meter, of the electric field in a typical laser. Or in other words : what are the typical amplitudes of the ...
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0answers
13 views

What dictates the range of EM radiation which can be produced by semi-conductor excitation (like LEDs)

Exciting semiconductors such as silicon carbide and gallium nitride can cause electroluminescence. I believe that by altering the chemistry of the semiconductor, you can alter the wavelength of the ...
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1answer
51 views

Does slowing light violate relativity?

Last year Scottish scientists managed to slow down photons in vacuum by changing their shape. Does this violate the special theory of relativity?
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1answer
28 views

Wave generated with particle excitement

To my understanding, an electromagnetic wave(infact two perpendicular fields) will be emitted when a particle(e-) shifts from higher energy orbital to lower energy orbital but what would be the ...
0
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1answer
67 views

Is it possible to strip the magnetic, or electric field from a photon?

A photon is made up of a magnetic part and an electric part, but we can see the existence of these fields without the other one so I would like to know if it is possible to somehow separate one field ...
2
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1answer
43 views

Characteristic room-temperature photon energy - is this nomogram wrong?

Reading this recent ars technica article on the James Webb telescope, something kept bothering me about the nomogram - shown below. The credit says it is from The Opensource Handbook of Nanoscience ...
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0answers
24 views

Is frictional heat just electromagnetic interactions creating infrared radiation?

Example: Rub your index finger on a sheet of paper and you will feel that it will get noticeably hotter Is the reason you feel this increase in heat (technically an increase in kinetic energy of the ...
0
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0answers
19 views

wave propagation modelling

what is the best modelling technique for modelling mm-wave propagation in electromagnetic environment. Right now,am working on how to use use Transmission-line matrix (TLM) and ray-tracing techniques
4
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1answer
69 views

From how far away could Earth's telescopes detect Earth like radio signals?

The Earth has been broadcasting human generated radio signals for about 100 years now. If a nearby civilization were broadcasting similar radio signals, could we detect them with our own radio ...
3
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1answer
35 views

Is every electric wave is an 'electromagnetic wave'?

Is every electric wave is an 'electromagnetic wave'? Why we only assume the electric field only?
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1answer
54 views

In a waveguide, where does the energy in attenuated waves go?

In an electromagnetic waveguide, there is generally a "cutoff frequency." Electromagnetic waves with a frequency that is lower than this cutoff frequency will not propagate at all -- i.e., they will ...
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1answer
23 views

When thermal IR gets reflected from an object, does it change its wavelength (frequency)

I'm working with thermal infrared (IR) cameras to detect human thermal radiation. I notice I can easily distinguish non-human objects throughout the camera's field of view, though all are at same room ...
3
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1answer
41 views

Momentum transfer of Light to Object

Can light made of photons in theory topple lets say a car? I know basic photon energy is hv where v is frequency. So according to conservation of linear momentum, if high enough and large amount of ...
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1answer
83 views

Characteristics of electromagnetic radiation

Is it possible to change the wavelength of an electromagnetic wave without a change of medium?
5
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1answer
59 views

Why are magnetron apertures in home microwaves so small?

I'm curious why magnetrons from a home microwave like in the image below can have an aperture between the magnetron cavity and the waveguide that is significantly smaller (2-6mm usually) than the ...
0
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0answers
55 views

What can I put in my microwave oven that won't get warm?

I have a fuzzy understanding that microwaves heat food because the waves interact with polar molecules in the food, causing them to vibrate, and the vibrations are heat? Correct me if I'm wrong. To ...
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1answer
34 views

How close do waves have to be for their wave functions to cancel? [closed]

I was thinking about waves canceling today and started wondering about this. Is there an equation relating the lateral separation of two identical but out of phase waves to how much they are canceled? ...
0
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3answers
222 views

aLIGO potential signals mimicking GWs not considered in the team publications? [closed]

[EDITED to accommodate info from the comments] Among the local atmospheric electromagnetic potential sources of a signal capable of mimicking the waveform of a GW not sufficiently considered by LIGO ...
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0answers
59 views

Do photons traverse through the vacuum of outer space as a helix? [duplicate]

I’m trying to understand “Electromagnetic waves”. If electromagnetic waves traverse as a helix then do photons traverse as a helix?
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5answers
96 views

How is the electromagnetic field made?

I know that an electric field is created by a particle with a charge and that a magnetic field is created by a moving charge but how do they combine to make a electromagnetic field?
6
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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 ...
0
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2answers
78 views

Why do electromagnetic waves diffract? [duplicate]

The expansion of electromagnetic waves due to diffraction can be easily explained with Huygens' principle (and in introductory courses this is usually how it is explained). But Huygens' principle is ...
0
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2answers
78 views

How does electromagnetic radiations penetrate?

I am reading about the discovery of subatomic structure which includes all these things radioactivity, alpha rays, gamma rays, x rays et cetera. I read that electromagnetic radiations are energy ...
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2answers
83 views
3
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1answer
89 views

Why are electric and magnetic fields perpendicular in an electromagnetic wave?

I want to know why electric and magnetic fields are perpendicular in an electromagnetic wave and what would happen if they weren't.
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1answer
37 views

Radiation frequency from an accelerated charged particle

My understanding is that a charged particle, when accelerated emits EM radiation. In a situation where a charged particle is briefly accelerated in a straight line it should produce a propagating ...
1
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1answer
111 views

What is the nature of the magnetic fields? [closed]

In this question, I am hoping to find out if there is an explanation to the magnetic hidden forces. In other words, what causes these fields? Is there any suggested theory, or any confirmed ones ? ...
0
votes
1answer
48 views

How to visualize electromagnetic waves?

Can someone please explain to me how to visualize an electromagnetic wave in 3D space? I have struggled for a long time now trying to understand how a WiFi signal could reach a device if it looks like ...
0
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2answers
33 views

How is it possible to even develop any current in an inductor?

Potential difference across an inductor (ie p.d. between current exit point and current entry point) is given as $$V= -L\frac{di}{dt} -iR,$$ where $L$ is the inductance of inductor and $R$ is its ...
0
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1answer
56 views

Vacuum chamber that prohibits EM wave propagation

Is it possible to create a vacuum chamber (something like vacuum tube) in which EM wave propagation is prohibited and EM radiation does not exist at all?
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1answer
70 views

How do integral representations of $\mathbf A$ and $\Phi$ satisfy Lorenz condition?

The following are the integral solutions of the potentials, obtained from the retarded potentials (by a Fourier transform): $$\mathbf A (\mathbf r) = \frac{\mu_0}{4\pi}\int_V \frac{\mathbf J (\mathbf ...
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0answers
4 views

does colour of compound affects the specific optical rotation at defined costant temperature and wavelength?

If analyte has a defined method of analysis for the Specific optical rotation. is it possible a change in specific optical rotation due to change in colour of same substance?
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7answers
1k views

What's the difference between mechanical and electromagnetic waves? [closed]

I have a life science degree and even worked in research for a few years. So I feel I should be able to answer this question for myself, but yesterday my daughter blindsided me by asking why, if sound ...
0
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1answer
48 views

Light waves and water waves

I have an idea and i would like to have more information: If I drop a stone in the water some rings or waves will appear. Those rings are made of water and are behaving that particular way because of ...
5
votes
4answers
113 views

What carries electric field through space?

A stationary charge "creates" a constant (but not uniform) electric field around it, and a moving charge "creates" a variable electric field around it. What "carries" the information about the ...
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2answers
40 views

What is the actual meaning of magnetic field and electric field in Electromagnetic waves?

I know that electromagnetic waves are composed of electric field and magnetic field but I don't understand what magnetic field is. Would you help me understand its physical meaning? What is the ...
0
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2answers
30 views

What is filtered through the linear polarization of EM light? E field, B field or both?

I know that for EM waves (i.e sunlight) for any E wave in any direction, there is B field perpendicular to it. However, when we pass that EM wave through the linear polarization filter, what actually ...
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0answers
68 views

Do all particles have radiative transitions?

Everybody knows that excited electrons can emit photons upon relaxation. A nucleus too (which is not an elementary particle), can be in an excited state and emit gamma rays upon relaxation: (source) ...
0
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0answers
32 views

Is an “underwater” submarine affected by a nuclear bomb exploding above the water? [duplicate]

I've just read Would being underwater help survive a nuclear bomb?. Submarines are way more armored and far from the surface than a human body (https://en.wikipedia.org/wiki/Submarine_depth_ratings), ...
0
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3answers
59 views

Do white light generated by light bulb also have significant Infrared intensity?

I am planning to obtain near infrared light for a project. Instead of producing the infrared myself, I thought it might be easier to use something inexpensive and commercially available. That's why I ...
0
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0answers
33 views

Phase noise measurement with an IQ mixer

I have a question regarding a measurement scheme of phase noise that I'm trying to implement. The idea is that I have two identical signal generators (I actually do) that generate a sinusoidal voltage ...
1
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1answer
48 views

Converting Stokes Parameters to Jones Vector

How do you convert a Stokes vector into a Jones vector? I am only concerned about fully polarised light, and I need to convert the Stokes parameters (or the azimuth and ellipticity angles) as measured ...