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)

4
votes
3answers
55 views

Radiation due to current

Generally we equate change in potential energy to change in kinetic energy but in case of a charged particle like electron this is inconsistent. Consider a case: An electron(of charge e)from rest is ...
1
vote
3answers
113 views

Where do the energy and momentum come from when light is perfectly reflected on a surface?

If you send a light beam to a surface which reflects the light perfectly I would say that on the surface is put a force of the light so the surface moves backwards. But where does that energy comes ...
2
votes
0answers
47 views

Have gravitational waves any effect on the electromagnetic waves in interferometers?

I am not into general relativity, but the explanation of how an interferometric gravitational antenna works is generally pretty basic. In the recently published paper announcing the detection of ...
1
vote
0answers
24 views

How will EM waves behave if they are made to pass through a region of intense magnetic/ electric field?

My question is exactly what the title says. I think they should not be affected as photons are uncharged. But shouldn't the oscillating Electric and Magnetic fields be affected by the electric/ ...
0
votes
0answers
75 views

Covering the whole world in an EMP

I recently thought about shutting down the whole worlds electronics, and naturally ended up with an EMP. I know that EMPs are generated when nuclear bombs explode, but nuclear bombs have some unwanted ...
0
votes
2answers
53 views

Is there an instrument that measures the Frequency of light directly

Is there an instrument that measures the frequency of light DIRECTLY? By "DIRECTLY" I mean without using any properties of the Wavelength.
1
vote
2answers
91 views

Non-standard representation of the free electromagnetic plane wave

The usual representation of a free electromagnetic wave in vacuum looks like this: The blue parts are the local electric field, while the green parts are the local magnetic field. The circularly ...
0
votes
0answers
41 views

Collimation and the inverse square law

This is my understanding of how the inverse square law applies to collimated light, and specifically laser light, since AFAIK it's the only light that can be collimated with any accuracy thanks to ...
0
votes
0answers
15 views

Can Obstruction of EM waves itself obstruct change in field?

Let us continue to accelerate a particle P, up and down: between two points X,Y in space(and, say, always in a symmetric manner relative to X,Y). Now, as I know, we'll be continuously dragging the ...
0
votes
1answer
42 views

Plane waves intensity

Our professor said that a plane wave has the same intensity in the plane perpendicular to it's propagation. I can't really make sense of how that is possible. I mean, shouldn't the intensity decrease ...
3
votes
0answers
48 views

Will the photon wavelength fluctuate in the presence of a gravitational wave?

The microwave background is due to the expansion of the Universe where the wavelengths of radiations are stretched by spacetime. As in the LIGO experiment, in the presence of gravitational wave, ...
0
votes
0answers
19 views

How to think about Ripple and Noise in circuits

Say you have a AC to DC power supply. If you were to hook an oscilloscope up you would see noise occurring. Some of it would appear to have a regular frequency in Khz or Mhz. Would this put off EM ...
1
vote
0answers
25 views

To which extent is the treatment of nuclear multipole radiation by the means of a classical electromagnetic field valid?

In the treatment of nuclear multipole radiation, for example in the context of nuclear gamma decay, it is standard, at least at the elementary level, to formalize the electromagnetic radiation as a ...
0
votes
2answers
41 views

Magnetic induction to generate EM waves

Let's say that I create a time varying magnetic field. This field then cuts a conducting circular loop normally. The loop has two protruding wires. Will the protruding wires emit EM waves? I ...
3
votes
1answer
104 views

How many photons are there in free space on average

Estimates of the amount of for example "dark matter" are of interest to the cosmologists. However, I have never seen an estimate of how many "free" photons could be speeding about in the known ...
0
votes
0answers
31 views

optoelectronics-smallest wavelength of light

Sorry this maybe a stupid question , but i need to know: A few minutes ago i have read an article about optoelectronics: worlds first optical single atom switch The writer of the article claims:"...
1
vote
0answers
38 views

What does this coordinate transformation in the Wave equation mean?

My tutor derived the following of which I do not understand the transformations (2.1) and (2.2): $$\Delta\vec{E} - \frac{1}{c^{2}} \frac{\partial^{2}\vec{E}}{\partial t^{2}} = \frac{4\pi}{c^{2}} \...
0
votes
1answer
81 views

What do we mean by wavelength of any electromagnetic wave?

What do we mean by wavelength of EMW? Wavelength of oscillating electric field or the oscillating magnetic field? Or is it that both the electric and magnetic field waves have same wavelength? If ...
1
vote
0answers
42 views

Implications for measurement of an initially localized free particle's wavefunction spreading out to infinity?

So, I have been attempting to wrap my head around what happens to a free particle that is initially localized to one spot. It seems that due to their different frequencies, the particle's wavefunction ...
4
votes
2answers
183 views

Why does a laser beam stay collimated?

I am looking for a simple way of explaining the collimation of a laser beam. The typical discussion of the two slit experiment of quantum theory relies heavily on the Huygens principle. Its ...
3
votes
0answers
81 views

Why must this boundary condition be met? (Electromagnetic wave at interface between two mediums)

My textbook says that The laws of Electromagnetic Theory (Section 3.1) lead to certain requirements that must be met by the fields, and they are referred to as the boundary conditions. ...
4
votes
1answer
74 views

The many faces of electromagnetic waves

In my waves and optics class, we have learned several ways to treat electromagnetic waves: light rays (geometric optics), electromagnetic plane waves, spherical waves, cylindrical waves (2D). One ...
0
votes
1answer
157 views

Is there any observational test that could be done to approve\ disapprove the Tired Light theory? [closed]

Tired light is alternative explanation for the redshift-distance relationship and for the metric expansion of space. The suggestion is if photons lost energy over time through collisions with other ...
0
votes
0answers
48 views

Experimental evidence for nonlinear electrodynamics

Has any experiment been conducted which shows that, above a certain threshold of field strength, electromagnetic interactions become nonlinear? If not, which field strength threshold is the one under ...
1
vote
1answer
27 views

Vanishing dipole radiation of equidistant point charges on a ring

I learned that if I distribute point charges uniformly on a circle and let them run along the circle with the same constant speed, the dipole radiation of that configuration vanishes. However, moving ...
3
votes
2answers
127 views

Does light interact with electric fields?

We know that light is an electromagnetic wave and it does interact with charges. It contains magnetic field and electric field oscillating perpendicularly but when we apply an electric or magnetic ...
1
vote
2answers
79 views

Will radio waves bend to reach receiver?

I was wondering if receivers just catch the radio waves that pass through, or if they actually attract the waves like a magnet. In other words, will a radio wave moving in a straight line bend in ...
0
votes
1answer
71 views

Will throwing oil on snow help it melt faster (significantly)? [closed]

The main thing that melts snow is the sun. Indeed, without the sun, the air itself would eventually turn to snow. The problem is, the sun melts snow inefficiently. The sun emits radiation (a lot of ...
0
votes
1answer
41 views

Electromagnetic plane waves [closed]

I have a question, a planewave impedance E/H =377 ohm, and it is said that for plane waves none of the components electric and magnetic dominates they are indistinguishable or same. But what about ...
1
vote
0answers
43 views

How can we detect particles?

A constant velocity particle (charged or uncharged) can only be detected if its velocity is made to change, e.g. by scattering another particle or radiation off it. If it's velocity remains constant, ...
3
votes
0answers
70 views

Estimating temperature with Boltzmann relation with split emission lines

I'm trying to estimate the temperature of a plasma through the use of hydrogen lines, $H_{\alpha}$ and $H_{\beta}$ using the Boltzmann relation: $$ \frac{ n_{2} }{ n_{1} } = \frac{ g_{2} }{ g_{1} }e^...
1
vote
0answers
50 views

WHY do waves diffract - what is the mechanism behind the diffraction?

Having recently studied wave diffraction at an introductory level, I don't feel that I understand why waves diffract like they do. What is it about the obstacle or the waves interaction with it which ...
1
vote
1answer
29 views

Quantim efficiency of a radio receiver

In optical communication we often know quantum efficiency of the receiver (probability of single photon detection and bitrate per photon). Are there any estimations on typical achievable quantum ...
1
vote
2answers
46 views

How can the position of charge be determined without EM waves?

The EM waves produced by accelerating charges can perhaps be used to locate the position of the charge, as usually done with the de Broglie waves. The stronger the oscillations of the electric and ...
4
votes
1answer
79 views

How do we know that light is made up of electric and magnetic fields? [duplicate]

What are the experiments that prove that light consists of electric and magnetic field oscillating perpendicular to each other. What are the experimental evidence we have for this theory of light ?
2
votes
2answers
69 views

When sunlight bounces off the Earth, why isn't the entire spectrum reflected rather than just the infrared portion?

I've read that greenhouse gases absorb and reemit sunlight, and that the infrared portion is what bounces off Earth back to space. When sunlight bounces off the Earth, why isn't the entire spectrum ...
0
votes
5answers
149 views

How to increase the frequency of light

If we want to increase the energy of the emitted photoelectrons (in P.E) then we should increase the energy of the photons which are related to the frequency of the light, so how is the frequency of ...
2
votes
2answers
125 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 ...
1
vote
1answer
67 views

Difference between reflection mechanisms in dielectric, metals and plasma

How the reflection and transmissions mechanism are different in metals, dielectric and plasma? I know that the density of free electrons is playing the role. Can anyone give an insight what is ...
3
votes
0answers
46 views

Why is the susceptibility $\chi(t)$ real?

So my question is quite simple I suppose, and perhaps trivial. It is known that the frequency domain susceptbility $\chi(\omega)$ is complex, and that the two parts can be related with the Kramers-...
0
votes
2answers
175 views

Can radio waves be stored in a device for future use? [closed]

Is it possible to store electromagnetic waves consisting of radio waves only without any other intermittent signals??
6
votes
1answer
612 views

How is a CCD able to collect images in drastically different lighting conditions?

I have read the basics of how a digital camera works. As much as I have understood, the digital cameras have a device called a CCD on which photons coming from the lens are incident. The CCD then ...
1
vote
1answer
33 views

Effectiveness of Layered EM wave shields [closed]

Which is best at shielding EM waves; a Faraday cage with sides made of blocks of metal, or layers of metal (with insulation ie plastic & without), or is there no difference between the three? &...
2
votes
6answers
162 views

Light in mass moving at high velocity

Imagine if you will, a strand of fiber optic cable 186,000 miles long. A pulse of light is sent through the stationary cable: it takes 1 second for light to travel the entire length of the cable. Now ...
1
vote
1answer
50 views

Does the wavefront in the double slit experiment represent the electric field of the EM radiation / light?

The question "What is a wavefront?" get the answer "A wavefront is a contiguous region of constant phase". This seems to be right for water waves as well as for electromagnetic radiation. But what is ...
1
vote
2answers
70 views

Are wave fronts in double-slit experiments moving forward? [closed]

I ask a question about "What is a wavefront?" which follows the question "What makes the radiation behind a slit coherent". For the wavefront it was answered, that "In electromagnetics ...(that are) ...
0
votes
3answers
103 views

What is a wavefront?

For this picture Anna wrote: "Incandescent light is incoherent because it comes from many sources and the same is true for sunlight. By passing the light through the one slit he created a single ...
1
vote
0answers
27 views

Can I emit light from an inductor? [duplicate]

As I understand it, inductors create a magnetic field when current flows through them, and light is an electromagnetic radiation. So, is it possible for an inductor to generate magnetic waves of the ...
0
votes
1answer
58 views

Electromagnetic Shielding of radio waves

Would a radio wave beam (perhaps a cm in diameter) with the same frequency as ordinary AM or FM radio waves and also the same voltage (v/m) have the same skin depth for any metal utilised to shield ...
3
votes
4answers
184 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 ...