"Photon" is the name given to particles of light in the quantum mechanical understanding. In interaction where the classical and quantum mechanical understandings of light agree they are fully equivalent to electromagnetic waves.
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Can the photoelectric effect be explained without photons?
Lamb 1969 states,
A misconception which most physicists acquire in their formative years is that the photoelectric effect requires the quantization of the electromagnetic field for its ...
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2answers
103 views
Why does the Sun feel hotter through a window?
I have this big window in my room that the Sun shines through every morning. When I wake up I usually notice that the Sunlight coming through my window feels hot. Much hotter than it normally does ...
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66 views
Photons: Collection of Wave Packets that produce a plane wave
Is it possible mathematically for photons, which behave as individual Gaussian wave packets, to combine in such a way that the approximate result is a plane wave at one particular frequency (i.e., the ...
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191 views
Born rule for photons: it works, but it shouldn't?
We can observe double-slit diffraction with photons, with light of such low intensity that only one photon is ever in flight at one time. On a sensitive CCD, each photon is observed at exactly one ...
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1answer
58 views
Equation for null geodesic around schwarzschild metric?
I'm trying to find the path of a photon around the Schwarzschild black hole, given its initial conditions. After much tribulation, I've basically given up on solving the equations by myself.
I just ...
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2answers
141 views
Discovery of $E=hf$?
How was the equation $E=hf$ discovered?
Was the proportional expression between energy and frequency of light $E\propto f$ discovered only by experiment? Or is there some logical(theoretical) senses ...
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1answer
35 views
Specific energy and specific angular momentum of photon
In this PDF [1], is made reference to specific energy and angular momentum of a particle. If the particle has no mass, like a photon, how should I define these terms in the equations further down for ...
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4answers
129 views
What happens when a photon hits a beamsplitter?
Yesterday I read that we can affect the path and the 'form' (particle or wave) of a photon after the fact (Wheeler's delayed choice experiment). Part of what is puzzling me is the beam-splitter. Are ...
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56 views
Do excited electrons drop back to same quantum state?
I'm trying to wrap my head around spectroscopy, therefore, I am looking for as complete an answer as possible here, hence why I have broken the question into a different points.
Here is what I know ...
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71 views
Photon Escape Angle From Black Hole
Consider a photon source emitting photons near the surface of a Schwarzschild black hole.
What angle, as a function of the source's radius from the event horizon, must the photons be emitted at such ...
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1answer
83 views
If time stops at the speed of light is a photon 'everywhere' at once? [duplicate]
I am not a physicist so excuse my question if it's paticularly stupid. As a particle gets closer to the speed of light time slows down as for that particle as compared to a reference from the ...
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Why is the photon emitted in the same direction as incoming radiation in Laser?
When an atom “lases” it always gives up its energy in the same direction and phase as the incoming light. Why does this happen? How can this be explained?
How does the photon generated because of ...
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57 views
Magnitude of a photon?
I encountered the following sentence in my textbook, which I don't quite understand, and after an unfruitful google search, I still can't figure out what they mean by magnitude in this context:
...
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28 views
How does optical phase modulation produce photons with different frequencies?
The classical description of electro-optic modulators is an index of refraction that depends on the applied voltage. For example, for a sine modulation $\sin(\Omega t)$, a monochromatic laser of ...
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1answer
64 views
Why is the Heisenberg Uncertainty Principle not obvious give the conservation of mass- energy?
A photons energy is given by $E=h *f$ and momentum $p=E/c$ (spin?) but the photon has no (rest) mass! Therefore it is the ultimate probing tool for looking at any mass position and velocity because ...
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1answer
30 views
Can we build a synthetic event horizon?
If we imagine ourselves to be a civilization capable of manipulating very heavy masses in arbitrary spatial and momentum configurations (because we have access to large amounts of motive force, for ...
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1answer
67 views
How do particles become entangled?
A person asked me this and I'm just a lowly physical chemist.
I used a classical analogy (how good or bad is this and how to fix?)
Basically, light has a net angular momentum of zero, insofar as ...
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1answer
112 views
Mass gap for photons
I am puzzled by the answers to the question:
What is a mass gap?
There, Ron Maimon's answer gives a clear-cut definition, which I suppose applies to any quantum field theory with Hamiltonian $H$, ...
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Contact electricity and photoelectric effect
Most universities provide an experiment about the photoelectric effect to determine $h$ by measuring the stop voltage against the light frequency and calculating the slope $h/e$.
But mostly they also ...
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Why doesn't light kill me?
I was attending my philosophy class and in the middle of student presentations, I found myself mentally wondering off and thinking about light. After a few minutes of trying to piece together how the ...
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21 views
Does quantum mechanics depend solely on electromagnetic waves? [duplicate]
I am beginning to learn quantum mechanics. Since determining the position of an object involves probing by electromagnetic waves and since i have read a simple derivation of Heisenberg's uncertainty ...
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3answers
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Precision of Coulomb's law
Up to which precision has the coulomb law proven to be true?
I.e. if you have two electrons in a vacuum chamber, 5 meters appart, have the third order terms been ruled out? Are there any theoretical ...
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1answer
83 views
How can we detect X-rays?
I know that X-rays can be detected by various ways, like ionizing of air particles.
Is there a way to detect X-rays,which are photons, by detecting ? Can something absorb the energy of the X-rays and ...
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1answer
108 views
Photons, where do they come from? [closed]
Photons, where do they come from?
What exactly is a photon?
I've certainly heard how they get produced, but it doesn't seem to make sense that some sort of particle should need to be produced just ...
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1answer
66 views
Is the de Broglie wavelength of a photon equal to the EM wavelength of the radiation?
Is the de Broglie (matter) wavelength $\lambda=\frac{h}{p}$ of a photon equal to the electromagnetic wavelength of the radiation?
I guess yes, but how come that photons have both a matter wave and an ...
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1answer
80 views
Difference between electromagnetic radiation (EMR) and Electromagnetic Field?
I'm a freshly graduated electrical engineer. One course that I really struggled with was Field Theory, because it was a lovely assortment of vector calculus and things that were explained to me well ...
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1answer
135 views
Why does Lorentz factor not hold for relativistic mass when we apply it to photons? [duplicate]
We know that the photon itself is massless particle $m_0=0$. But we also know, that the mass of the objects does increase with their energy. And we know that under certain circumstances (gravity, ...
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1answer
82 views
In solar cells, do photons break apart electron-hole pairs, or create them?
Some sources say that when a photon hits the PV cell, it breaks apart electron-hole pairs. Other sources say that photons create electron-hole pairs. Can anyone explain which one is right? I've read ...
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23 views
Energy needed to raise energy level of an atom? [duplicate]
Suppose I have an atom at rest which is at energy level $E_i$. Would it be possible to raise it to the next higher level $E_{i+1}$ by shooting a photon of energy $E_{i+1}-E_i$ at it?
I ask because ...
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1answer
97 views
Where is the amplitude of electromagnetic waves in the equation of energy of e/m waves? [duplicate]
Does the amplitude of the photon oscillations always stay constant and if it is not - what are the physical differences between the photon with higher amplitude in comparison to the one with the less ...
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1answer
53 views
EM Waves Energy Loss
Where does the energy go when two photons interfere destructively at a point on a screen in Young's double slit experiment ?
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Physical significance of effective wave function
In Yanhua Shih's book on quantum optics, the coherence functions are expressed in terms of effective wave function. Here are the expressions for single photon wave packets.
To derive the coherence ...
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1answer
568 views
Neutrinos vs. Photons: Who wins the race across the galaxy?
Inspired by the wording of this answer, a thought occurred to me. If a photon and a neutrino were to race along a significant stretch of our actual galaxy, which would win the race?
Now, neutrinos ...
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3answers
43 views
Interaction photons-matter and dimensional analysis
I know that when photons pass through matter, the law that describes the intensity in function of the thickness is:
$$I(x)=I_0 e^{-\mu x}$$
where $\mu = \rho \frac{N_a}{A} \sigma$ and ...
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2answers
111 views
Do photons have mass? [duplicate]
As a student in a highschool physics class, my teacher has repeatedly told me that photons are massless. Yet, I have also heard from other sources that photons have momentum. If photons were to have ...
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49 views
How does QED deal with wavelength of quanta [duplicate]
Since QED treats photons as individual units (quanta) how does it treat the concept of the "wavelength" associated with the photon?
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1answer
101 views
Finding the maximum kinetic energy of any photoelectrons?
An incident photon, $f=5.5\times 10^{14}\ Hz$, hits a metal with a work function of $2.8\ eV$.
Find the maximum kinetic energy of any photo-electrons (in Joules).
I'm confused exactly how to do ...
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1answer
42 views
Color of a Metal's Threshold Wavelength?
How do I find the color of the threshold wavelength if the metal has a threshold wavelength of $\mathrm{6.5\times 10^{-7}m}$? I know that converts down to $\mathrm{650\ nm}$, but can I still use the ...
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1answer
28 views
Color of an incident photon?
If the incident light at 360nm causes photoemission of electrons, wouldn't the color be ultraviolet? I know that really isn't a color, but that's what my chart of the light spectrum says.
Unless I ...
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1answer
167 views
How the inverse square law in electrodynamics is related to photon mass?
I have read somewhere that one of the tests of the inverse square law is to assume nonzero mass for photon and then, by finding a maximum limit for it , determine a maximum possible error in ...
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What is the cause the light is affected by gravity? [duplicate]
I know that photons have no mass and that a photons exist only moving at the speed of light. So what is the cause that a massive astronomical object can bend a ray of light?
I have two thoughts, but I ...
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2answers
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Transfer of electron energy to atoms (heating up of matter by absorption of photons)
If an electron absorbs a photon to get exited to a higher energy level, it should either come back to same state or any other lower state by emitting the required photon. How then can there be a net ...
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110 views
What is the mass of a photon moving at the speed of light? [duplicate]
What is the mass of a photon moving at the speed of light?
And if it does not have mass, how is it affected by gravity?
Also why does Einstein's general relativity support that a gravitational wave ...
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0answers
78 views
Conservation of Angular Momentum: atomic transitions vs exciton decay
I have a question about the role of photon angular momentum in two different sets of selection rules:
In atomic transitions within the dipole approximation, I've seen the selection rule as:
$\Delta ...
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2answers
117 views
Seeing colors: photons vs waves
As an atmospheric physics major I am familiar with electromagnetic radiation in the atmosphere and what dictates what wavelength objects will emit at. When observing radiation in the atmosphere it is ...
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3answers
244 views
Does a photon have mass? [duplicate]
I have seen questions assume photons have no mass. But I have not seen any questions that directly ask whether or not photons have mass.
If photons have no mass, then how do they occupy space? How ...
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0answers
105 views
Quantum Electrodynamics
I was wondering if anyone could give a simple explanation of how light interacts with matter. From what I have read in QED, electrons will repel each other because of their ability to emit and ...
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182 views
Are there “gaps” in light, or will it hit everywhere?
Not sure how to word my question.
Picture a light source in vacuum, so nothing disturbs the light (or similar conditions), 2d.
If I move very, very far away, will it happen that some of the light ...
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1answer
39 views
hurdles in creating (close to) infinite images
Let's put an object(hypothetical superman) inside a "well sealed" box containing only mirrors. Is it possible to create number of images that will be close to infinity, assuming that resolution of our ...
4
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1answer
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Are there 2 kinds of photons, one that mediate the electromagnetic interaction and the other the quanta of light?
It is usually said that photons are the force carriers or the mediators of the electromagnetic forces between electric charges. At the same time we know also that electromagnetic waves on the quantum ...
