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

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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 ...
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39 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 ...
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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
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), ...
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6k views

Is it really possible to break the speed of light by flicking your wrist with a laser pointer?

Minutephysics has a popular YouTube video called "How to break the speed of light". In the video it states that if you flick your wrist while pointing a laser that reaches the moon, that the spot of ...
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1answer
56 views

Emission of Characteristic X Rays

X-rays are emitted when high velocity electrons in an X-ray tube collide with a metal target. Some high velocity electrons on collision with the metal atoms cause an inner electron of an atom to be ...
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3answers
58 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 ...
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1answer
43 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 ...
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0answers
32 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 ...
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1answer
80 views

Does the complex conjugate of a vector have the same direction as the vector?

Looking at reflected and transmitted optic waves, the $\overset{\rightharpoonup }{E}_t$ vector is always perpendicular to $\overset{\rightharpoonup }{k}_t$ (as seen in the attached image). So ...
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1answer
32 views

Evanescent waves in Vacuum

I would like to know why evanescent waves are not possible in pure vacuum? Indeed, we have $$ k^2 = (\frac{\omega}{c})^2 $$ in vacuum, so we could have for example : $$ ...
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12 views

System of two perfect isolated bodies and infrared death

What is the theory about a system of two bodies, which is perfect isolated from the environment? Take it as a Gedankenexperiment, where the two bodies are not perfect reflectors but the isolating ...
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3answers
80 views

Effect of Gravitational Waves on light?

We all know about the gravitational lensing effect. From the analogy of fabric of space time used to explain this concept to laymen like me, i understand that light follows the curvature of spacetime. ...
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3answers
94 views

Can light escape a black hole? [duplicate]

I heard that a black hole is not black because it's escape velocity is greater than or equals to the speed of light. But instead it is black because the light that gets emitted from a black hole gets ...
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1answer
55 views

Concentrating the Sun with mirrors facing each other

What will happen if the sun is concentrated by directing sunlight to mirrors that are facing each other? i know that mirrors absorb light and dont reflect 100% but will the efficiency increase due to ...
3
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0answers
19 views

Determination of temperature from electromagnetic emissions

The actual measured radiation intensity at different frequencies varies significantly from the ideal theoretical Planck curve. For example, here is the result of a typical laboratory measurement at ...
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2answers
105 views

Does light have mass? [closed]

Does light have mass? If yes, will it exert force? If no, then how are light particles are travelling at light speed? If light doesn't have mass how is it attracted by gravitational force (black ...
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1answer
56 views

Temperature from gamma rays?

I was reading about gamma ray bursts and read something along the lines of 1 MeV gamma rays corresponding to a fireball above 2 billion degrees Celsius. How do scientists get temperature from that? ...
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3answers
53 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 ...
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3answers
18k views

Temperature behavior over time of black or white cars in hot, sunny regions

How does the color of a car influence its inner temperature change over time when parked outside in windless, hot and sunny regions? I know what's the common idea about that: black cars are supposed ...
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3answers
106 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 ...
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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 ...
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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/ ...
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72 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 ...
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2answers
51 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.
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2answers
86 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 ...
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0answers
34 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 ...
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13 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 ...
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1answer
39 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 ...
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0answers
47 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, ...
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1answer
3k views

Force on Earth due to Sun's radiation pressure

I have been asked by my Classical Electrodynamics professor to calculate the force that the Sun exerts in the Earth's surface due to its radiation pressure supposing that all radiation is absorbed and ...
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3answers
86 views

FWHM increase with energy (gamma spectra)

Below I have two plots from a gamma spectrum which I've been analyzing. The first plot is between a low energy range, the second between a significantly higher energy range. It is clear that the FWHMs ...
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8answers
3k views

What are the various physical mechanisms for energy transfer to the photon during blackbody emission?

By conservation of energy, the solid is left in a lower energy state following emission of a photon. Clearly absorption and emission balance at thermal equilibrium, however, thermodynamic equilibrium ...
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7answers
9k views

Why does light change direction when it travels through glass?

This was explained to me many years ago, by a physics teacher, with the following analogy: "If someone on the beach wants to reach someone else that is in the water, they will try to travel as much ...
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0answers
18 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 ...
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217 views

What does electric field of unpolarized light look like when measured?

When we talk about fermions in mixed state, we say that their state can't be described by a wavefunction and just compute all the probabilities using density matrix. That's OK because the ...
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5answers
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How is a vacuum able to propagate light?

We say that sound waves need a medium to propagate and we know that light doesn't need such a thing. But is that really how that works? There's no such thing as "nothing" according to Quantum ...
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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 ...
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2answers
39 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 ...
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2answers
131 views

How to represent a laser pulse in quantum optics

Every quantum optics textbook that I've found says something like "a coherent state represents the output of a laser", but a coherent state is a static thing (aside from the oscillating phase of the ...
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1answer
77 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 ...
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5answers
3k views

Do the electric and magnetic components of an electromagnetic wave really generate each other?

Frequently when EM waves are taught, it is said that the change in electric field causes a change in the magnetic field, which then causes a change in the electric field, and so on and so forth. But ...
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0answers
30 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 ...
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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}} ...
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1answer
79 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 ...
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2answers
165 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 ...
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40 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 ...
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1answer
153 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 ...
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2answers
141 views

How can one meaningfully say that one field generates the other in an EM-wave?

This is a follow up question to: Do the electric and magnetic components of an electromagnetic wave really generate each other? Clearly there are nuances of how one states the "mutual induction" ...
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2answers
240 views

What electromagnetic wave produces the strongest electrical current when making contact with an element?

More specifically, what electromagnetic waves can we utilize to generate electrical power and out of those waves, which one would produce the most power? Additionally, which one would be the most ...