Photon Definition and 1000 Threads

How photon transfer energy to electron in case of photoelectric effect,and compton effect. Is any high level theory which explains this scenario?

Photons do not have mass, so why stop at 299700 km/s??

We're told that all electromagnetic radiation consists of photons. But you never hear them mentioned when discussing low-frequency radio waves. Why not? I get that, due to the low frequencies, the energy of each individual photon would be very small, so there must be lots and lots of them flying...

If I understand it correctly, the proper time differential for a photon in flat space is zero. That is evident if the velocity of light is equal to c, so the right hand side of the Minkowski metric is equal to zero. Therefore the left side must also be zero. My question: Is the same true for...

Wiki states: Photon upconversion (UC) is a process in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength. https://en.wikipedia.org/wiki/Photon_upconversion Is it possible to have the emitted light with the...

<< Mentor Note -- thread moved from the technical forums, so no Homework Help Template is shown >> Let's say you have a laser cavity with two mirrors at either end, one is considered 100% reflective, the other 99.9%, so that a wave beam is emitted through this lower reflectivity mirror. I know...

Hi everyone, I have a few questions about the composition of light: First, what is it? Is white light the result of all color wavelengths present in an area? Second, if so, then why is there no interference in waves of light (or is there)? Third, if photons all travel at the same speed, then...

I am wondering what would be an experiment demonstrating that photon parity is -1. It also occurs to me that one might deduce the parity from Maxwell's equations, though that might be a bit of a stretch since they are classical of course. Also, it occurs to me that parity might be assigned a...

If we pose a hypothetical universe end-state very cold, where only very low energy photons are left. Could these photons undergo a phase transition into something like a BEC? Would they gain invariant mass if they did (become a condensate) Could someone show why this would/would not happen...

Hi, if I read the article (see link) I get confused: Is it emission or reflection? If it is emission, how is it possible that the photons are emitted to one side? (Unfortenately I do not have access to the original article.)...

I couldn't type the whole question | -or jusg part of the spectrum during the working of a solar panel

Maria Goeppert-Mayer described the theoretical foundation for 2-photon excitation and it was later proven correct with the advent of lasers. Today, two-photon microscopy uses this quantum physics principle. For example, if you want to excite a fluorophore that has an excitation peak at 495...

I'm trying to understand the time delay induced on each photon when several individual photons travel in an open space from a sender to a receiver for example in the application of Quantum Key Distribution. So what I understand so far is light(photon) travel around 299,792 km (186,282 miles) per...

i'm wondering about the differences in oscillations between a photon and neutrino, does a neutrino have a wider probability range (or a greater amplitude for a possible location than does a photon) how do the probability ranges for a photon and a neutrino compare when not looking at wavelength...

Other than relativity is there any theory, proof, experiment, etc. that tells us a photon has no mass? i.e. Is the concept of zero mass solely derived from relativity

Really silly question, but if we assume that our current science is correct, is it plausible that we can move faster than light in a vacuum? Say, for example, can we make the mass of something less than a photon so it then can it move faster than light in a vacuum. I know this sounds like a...

I am about to teach some of an introductory course for bachelor students in the field of medical physics. More specifically the topic "Photon and charged particle interactions with matter" in respect to radiation therapy (again, medical physics). I know there are a lot of topics within radiation...

Greg Bernhardt submitted a new PF Insights post The Schwarzschild Metric: Part 2, The Photon Sphere Continue reading the Original PF Insights Post.

Homework Statement Homework EquationsThe Attempt at a Solution Since energy of photon is very low compared to the rest mass energy of the nucleus, I consider non – relativistic calculation. Conservation of linear momentum gives : momentum of nucleus = momentum of photon = p...(1)...

If a (polarized) photon is absorbed by a polarization filter, does its energy go into the filter? I am wondering if that is the case to obey conservation laws. And if it passes, is its original polarisation direction somehow conserved?

Hi everyone, I just have some confusion regarding Planck's and Einstein's equation. The following is an explanation of the photoelectric effect using Einsteins theory: Light is composed of photons. Each photon has energy hf and mass hf/c^2. When ultraviolet photons are brought to rest by zinc...

Hello, There is a thing I struggle to understand on laser physics. There is a modulation method called direct modulation for semiconductor lasers where by changing the current we modulate the light which is emitted form the laser cavity. There is a picture below It is stated in...

Hi! We will make a lab analogous to the stern gerlach experiments but with polarized light. How can we get only one single photon in experiment with a coherent light source? I'm going to make a lab where we need to get in only one single photo at a time. I have read that you can use some...

... where was our current place in spacetime, call it A, when that photon started its journey 12 by ago? Did A even exist 12 by ago?

I would like to know the results of a few scenarios with a beam splitter. (1) You send a single photon through a half silvered mirror with a reflector at either side, as above, but instead of having two detectors, and a 50% chance of either going off, you just have one detector, and where...

Hello, I have always been curious about physics and decided to try this forum. However I am a bit concerned due to my lack of knowledge on the subject, so I’m hoping my questions won’t be unacceptable for the forum. I have always wondered about photons and how they interact with the world. If I...

I've been googling this and can't come up with a direct answer. Can a gluon emit a photon? I know. 1. All Standard Model particles with mass interact via the weak force. 2. All quarks and gluons interact via the strong force. 3. All quarks, charged leptons and massive weak force bosons emit...

A double covalent bond of nitrogen (N2) is 15.58eV Now let's go into a example. if i have a laser that is 477nm and i do 1240/477nm then i get 2.6eV per photon. Now if i do (15.58eV / 2.6eV) it equals ~6 photons. Now to figure out how many Joules are required for 1 photon I do (6.626*10^-34S *...

Homework Statement An atom or ion with only one electron is excited from the ground state to the first excited state (n = 2) with a photon of 1.47E-17 J of energy. What is the charge on the one-electron species? A. 0 B. +1 C. +2 D. +3 E. +4 Homework Equations E=-(2.18E-18)(Z2)/(N2) The...

1. The problem statement, all variables, and given/known data After thinking over your beloved but erratic instructor’s lectures on the Bohr model of the atom, you come to the sad but inevitable conclusion that he has, yet again, lied to you. You have been taught that to make an electronic...

Does anyone know of a simple relation between dark current and dark count in photon collection devices?

Entangled photons in superposition state : | Ψ} = (|HV} - | VH})/1/√2 are sent from source to polarizers and then to detectors A and B ( in this setup distance from source to detectors is equal). If A measures vertical photon she knows immediately that B photon must be horizontally...

I realize this type of question has been asked elsewhere on competitor websites but I want to make it more precise. Usually, the person asks if anything in QM is possible to which the answer is no, for example, a photon cannot have spin 0, hence some things in QM are impossible. But what about...

Since proper time for photons doesn't change, i.e. in their reference frame time doesn't change, then it should be that photons don't change their quantum mechanical state, or the equivalent in Maxwell's theory. One could say, well they don't experience time, but we do. Okay, but since their...

In what condition does a photon hit a proton? What happens to the energy of the photon in that case? Does proton emit another photon and goes down to the initial energy state?

If you search for "does a photon experience time", almost every other link says that they travel at the speed of light and so STR tells us that its clock doesn't tick at all. However why do they use the arguments for special relativity which was developed for massive particles moving close to...

I'm looking at the possibility of trying to measure the length of photons as a Science Fair project. I know that photons are often considered to be "point particles", and I know there are fundamental limits on measurements due to uncertainty in position and momentum. I also know that according...

In the photon version of the EPR experiment, how is the final polarization state of the photon detected? I have read a number of high level descriptions of the EPR experiment, but I am having trouble with understanding the detection part. Here is my understanding, please correct me where I am...

This page doesn't explain it well imo. How does quantum entanglement convey info? http://science.howstuffworks.com/science-vs-myth/everyday-myths/teleportation1.htm

Is it fair to say that the photon does not follow the rules of Special Relativity? I ask this because the photon relative to all other frames of reference has zero mass even though it is traveling at the speed of light. If we increase the speed of any other particle to the speed of light its...

Due to Compton - Scattering it seems that a Photon changes the Momentum of the electron, although it doesn't have any mass. How should I imagine this?

Can anyone counter my argument that the photon energy is properly half of the generally accepted value? It is a short argument, as follows: Accepting the Planck hypothesis that the energy of the standing-wave electromagnetic modes of a cavity oscillator at thermodynamic equilibrium is E = n h...

Hello all, disclaimer here, I haven't taken quantum mechanics yet, all I know of it comes form books and PBS Space Time Series. Since a photon can, at any given instant, "split" into an Electron-Positron pair, does it mean that if this occurs between point a and b, the measured speed o that...

Note: added to the title should be "and a particle description". ## \\ ## The intensity (energy density) of an electromagnetic wave is proportional to the second power of the electric field amplitude, i.e. intensity ## I=n \, E^2 ##, apart from proportionality constants. Meanwhile the energy...

My aim is to derive the photon propagator in an Coulomb gauge following Pokorski's book method. In this book the photon propagator in Lorenz gauge was obtained as follows: Lorenz gauge: ##\partial_{\mu}A^{\mu}=0## It's proved that ##\delta_{\mu}A^{\mu}_T=0##, where...

If a photon leaves a source 4,2 light years away how far apart will it be from a similar photon it was adjacent to (say less than 10^3 wavelengths) when it departed. Does the inverse square law mean that individual photons get further apart and stay the same size or do they occupy a larger space...

I haven't though about this from such a perspective but today while reading wikipedia (yes yes not the best source) I got confused, now the "eV" is said to measure the energy gained by an electron between a potential difference of 1V. I assume particle physicists use this measurement because its...

I think we can all agree that when we are shooting many photons one by one, through an interferometer, we can eventually land up with the interference pattern. This can be explained by saying that two photons combining in some areas to give four photons and in some places annihilating each...

After an electron absorbs a photon, it will move to a higher energy state. It then releases a photon and returns to its ground state. But why does the electron release the photon? Why does it not remain in that energy state? What forces it to return to ground state?

Hello, I read that in a scintillator before the photomultiplier tube is a crystal or sometimes gas or even sometimes a plastic, in other words a material which exerts luminosity under ionizing radiation. Say in the doped crystal for example, a high energy photon of say several Mev hits the...