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

learn more… | top users | synonyms (2)

3
votes
2answers
53 views

Can we see/detect things which don't have electrons

Whenever we sees a thing the process happening at atomic level is the electrons of that stuff absorbs the energy from packets and goes to higher state and then comes to ground state and emits ...
-1
votes
0answers
15 views

What are the effects of an electromagnetic wave on a moving charge? [on hold]

Just want to know the effects with relation to the resulting velocities and positions.
6
votes
8answers
2k views

Prove that an electron in a hydrogen atom doesn't emit radiation [duplicate]

According to electrodynamics, accelerating charged particles emit electromagnetic radiation. I'm asking myself if the electron in an hydrogen atom emits such radiation. In How can one describe ...
-3
votes
0answers
45 views

Why does the Microwave disturb the Internet Signal?

I have no back round in physics but was wondering how come every time the microwave is turned on, the internet slows down dramatically?
4
votes
3answers
503 views

Is there any effect on mechanical waves by electromagnetic waves (and vise versa)?

Do electromagnetic waves like light and gravitational waves (due to moon for instance) affect on mechanical waves like sound? Can sound change the path of light?
1
vote
0answers
37 views

Is it possible in this Universe to communicate a bit of information with energy that scales sub-linearly with distance?

If we look at all the ways that people do communicate information, they all seem to have a cost "at least linear in distance." For example, communicating over a wire has attenutation, so the energy ...
-1
votes
0answers
24 views

Can I make a microwave oven case from expanded metal? [closed]

I want to replace the solid walls of a microwave oven with expanded metal (mesh). From what I have researched if you have a maximum mesh size of 10% of the wavelength, a mesh will act as a faraday ...
-1
votes
2answers
58 views

How do signals go through solid objects? [closed]

So many types of signals pass, or seem to pass I don't know, through solid objects. How do they do this?
2
votes
3answers
64 views

How to distinguish light rays coming from objects of different material

Motivation: My major focus is on Digital Image Processing (specifically segmentation). Due to external noise, the different parts of an image are not fully quantized. Therefore, various segmentation ...
-1
votes
0answers
22 views

Pound and Rebka experiment and redshift

The difference in the emission frequency from the frequency at the receiver is explained by the shift of this frequency during movement in a changing gravitational potential (see John Rennie's ...
3
votes
2answers
126 views

Minimum frequency of an electromagnetic wave

Is it possible to create an electromagnetic wave of near zero frequency? An electromagnetic wave carries energy. If we can make the frequency of an EM wave vanishingly small and make it practicality ...
3
votes
1answer
90 views

Why doesn't a uniformly moving particle radiate?

When considering a uniformly moving charged particle, we have the following fields: $$\vec E = \frac{q(1-\beta^2)}{4\pi\epsilon R_a}\vec R$$ $$\vec B = \frac{1}{c^2}\vec u \times \vec E$$ With $\vec ...
0
votes
2answers
35 views

Data center copper shielding

I have a data center (5m*5m*3m) wall shielding of copper foils with a width of 1m and thickness of 1mm and overlap of 10cm for each two foil stuck to the walls. I have three questions. 1) Could this ...
1
vote
0answers
60 views

Why are FM radio waves less susuceptible to interference than AM? [duplicate]

When studying modulation of radio waves (or of most electromagnetic waves for that matter) I came across that question. Why are FM waves less susceptible to interference than AM waves? I know that in ...
0
votes
0answers
15 views

Spontaneous Parametric Down Conversion and the direction of the electric field component

The Spontaneous Parametric Down Conversion process is used to produce a pair of entangled photons. For this photons their electric field components are perfect adjusted by 90°. But the directions are ...
2
votes
2answers
46 views

Does a circularly polarized electromagnetic wave transfer angular momentum from the transmitter to a receiving antennae?

This question is about the rotation of macroscopic objects and looks at the magnetic vector of an electromagnetic wave. As basis for comparison, we consider an induction motor. The stator induces a ...
1
vote
1answer
60 views

Why do particles moving in circular motion emit em radiation? [duplicate]

For example particles moving in a synchrotron . Which energy of the particle is converted to the energy of the radiation ? What is the relation between this energy and the change in direction of the ...
0
votes
1answer
33 views

Relation between carrier frequency and data transfer rate?

Is there a relation between the frequency of electromagnetic waves and the rate at which it can carry information? If yes, then what it is and why it is?
0
votes
1answer
46 views

Electromagnetic waves of accelerating charges

Is it true that more accelerating a charge will cause electromagnetic waves of more energy than the energy of the electromagnetic waves cause by lesser accelerated charge ?
1
vote
0answers
66 views

Time involved in reflection

Consider light bouncing back and forth between two ideal front surfaced mirrors. How long does the process of reflection (i.e., absorption and re-emission) take?
0
votes
2answers
35 views

Electromagnetic waves and their extremes

Why do we have electromagnetic waves only in the wave lengths between 10^2 to 10^-14 metres respectively from radio to gamma waves.? Does any scientific reason exist for that? If it is not so, Does ...
1
vote
0answers
30 views

Can accelerated charged particle gain energy from charged medium? [closed]

Suppose a charged particle is moving in a medium. If it is accelerated, it is well known that it radiates energy (even in the vacuum). I was wondering if the charged particle would accelerate through ...
0
votes
0answers
47 views

Skin depth and electromagnetic shielding

The term "Skin Depth" refers to the the depth upto which current flows from the surface of an AC-current-carrying conductor. This depth is inversely related to the frequency of the current. Does this ...
3
votes
1answer
41 views

Antennas and the electromagnetic field

I'm an electrical engineering undergrad and have some questions about radio antennas. We've just covered the electronics and maths of radio theory once the signal has reached the receiver, I'm ...
3
votes
1answer
64 views

A Question on energy of electromagnetic wave

( I initially started to ask, "since according to Quantum-theory of light; the energy of a photon, depends only on the frequency of light-wave (E = h * nu), and no-mention of amplitude. So, does the ...
1
vote
0answers
56 views

Why is 2000 grit good enough for a mirror finish?

The mean particles size on a 2000 grit sandpaper is ~ 1 um, which is not that smooth compared with the wavelength of visible light. But usually when I want a mirror finish, 2000 grit will provide a ...
0
votes
0answers
14 views

How to find the polarization (phase) of the virtual source if image theory is used

Consider a radiating element (actual source) is placed above a ground plane, and if we apply image theory to determine the E-filed, the virtual source will be placed below the ground plane and ground ...
0
votes
1answer
28 views

WHY are reflections stronger at an angle acording to the Fresnel equation?

When looking straight at a glass surface you can mostly see through it, but if you look at it at an angle it becomes more and more like a mirror surface. This is described by the Fresnel equation, or ...
1
vote
1answer
42 views

Can We “Tune” The Radiation Output Of a Nuclear Device.?

After reading "Project Orion", the 1950's plan to launch a large mass spaceship using small nuclear devices, (and also from common sense), I realise that a lot of nuclear research is classified. The ...
5
votes
3answers
107 views

Energy of an accelerated charge?

Thought experiment: Let's take a positively charged particle and place it in a vacuum with no electric field. It just sits there. Now, we instantaneously introduce an electric field. The moment ...
1
vote
1answer
42 views

How do we filter out radiation from galaxies from the cosmic background radiation?

When a whole sky view is done to get a picture of the cosmic background radiation the radiation from our Galaxy is filtered out, and we are left with a picture which show radiation coming, more or ...
1
vote
3answers
99 views

What is the amplitude of a light wave?

Referring to this question How can I measure the amplitude of a light wave? I'm curious about what is a amplitude of a light wave. Especially for light from a thermic source.
3
votes
1answer
70 views

How can I measure the amplitude of a light wave?

Suppose I have a light wave and I want to measure its amplitude, or check to see if it has an amplitude of a certain value: how would one go about doing this?
3
votes
1answer
101 views

Validity of the 'photon wavetrain' model of coherence

In some optics textbooks, coherence is introduced with the "photon wavetrain" model. In this model, we consider light generated by many atoms each making the same transition. During each transition, a ...
2
votes
1answer
35 views

Is it possible that propagation of acustic waves leads to emission of radiation?

Question: Consider large cloud of gas. Assume it is electrically neutral (but as always, matter is composed of smaller things which are actually charged). Is it possible that propagation of sound ...
0
votes
1answer
24 views

Absorption spectra of molecules library

Do you know where I can find a library with absorption spectra? I would like it if then I could input a wavelength and get back a specific value. More specifically I would like to see the absorption ...
1
vote
1answer
42 views

A Formula for the Phase Difference Between the Electric and Magnetic Wave Oscillations?

A) Is there a formula for the phase difference between the electric and magnetic field oscillations, in vacuum, in an electromagnetic wave emitted from an antenna, as a function of the frequency the ...
0
votes
0answers
27 views

Does a cathode ray tube emits electromagnetic waves from a steady DC electron beam?

In cathode ray tube, heated cathode emits stream of electrons but when I wrap a coil around tube a current will be inducted in that coil? after all electron beam is a steady DC current? so no emf?
2
votes
2answers
24 views

Should static electricity affect a Crookes radiometer?

I've been playing around with a Crookes radiometer for fun and I happened across something I can't figure out. I know the fundamentals of the radiometer (e.g. partial vacuum, thermodynamics, etc.), ...
3
votes
2answers
52 views

Possible Safe Areas In a Solar Flare

Which part of the earth would be the safest in case of the major solar flare? Will it be near equator or something like that?
8
votes
2answers
150 views

Can the question of a gravitationally accelerated charge radiation be tested experimentally?

I know that the question of radiation from a gravitationally accelerated charge has been discussed extensively at Does a charged particle accelerating in a gravitational field radiate?. Yet the ...
3
votes
1answer
457 views

Can we use radiation pressure to push/levitate a human?

I want to know, at least in theory, are there any safe em wavelength that could affect human body as net force and do no harm? To put it bluntly I want to know is it possible for levitate a human on ...
6
votes
2answers
101 views

Will accelerated observer see radiation from the charge that is at rest in observers's frame?

So I had a huge debate about this with my friends. Imagine that you are in a non-inertial frame of reference. For simplicity, assume that frame is accelerated along x-axis. You have held a charge in ...
4
votes
4answers
156 views

How do light waves get their size?

An atom or (small) molecule has the size of about 100pm. Elektromagnetic waves range from about 0.1nm up to 1 km. The most common way waves (like light) are caused by 'jumping' electrons to another ...
-1
votes
1answer
32 views

Are stainless steel more radiation absorption than carbon steel?

Are stainless steel more radiation absorption than carbon steel? and if it is so why?
0
votes
0answers
13 views

Directivity of dipole antennas inconsistency

I'm trying to model the directivity of dipole antennas of differing lengths. There are two main ways I've thought to approach this. The predicted radiation pattern is given by $$P_{\mathrm{predicted}...
0
votes
1answer
33 views

What happens when an electromagnetic wave passes through a magnet or charged capacitor?

What are the effects or interactions between propagating electromagnetic wave that passes through static magnetic field (big neodymium magnet) or static electric field (charged plates of HV capacitor)?...
4
votes
0answers
56 views

Seeing light source from its diffracted light

Even if the line of sight is blocked by something(like a wall as in figure) will I able to see the light source if I see the diffracted light of the source? 1.Will the observer no. 2 see the light ...
0
votes
2answers
24 views

Gamma spectroscopy - Nuclide identification

I have a question about what the usual practice is for nuclide identification in gamma spectroscopy. For example, if I see a line at 477 keV, I would write that the origin of this line is $^7Be$. As ...
7
votes
3answers
645 views

Cooling down to absolute zero by radiation

Consider a system consisting of a gas, it is put in a container which is permits transmission of all kinds of electromagnetic waves. If this system is isolated and put in a perfect vacuum, and left ...