Electron Definition and 999 Threads

Specifically, this would be beta plus decay and not electron capture, and assumes an electrically neutral radionuclide. Since beta plus decay is the emission of a positron from the nucleus as a proton transmutes into a neutron, the resulting atom now has 1 less elementary charge than before, but...

How to correctly determine the temperature of electrons in an ion source based on ECR? Is it possible to use the Saha equation? ##\frac{n_en_i}{n_a}=\frac{g_eg_i}{g_a}*3*10^{21} T^{3/2} e^{-J/T}## Using the search, I found the McWhirter criterion for the applicability of the formula above: ##n_e...

As in title: Plugging in the definition is straight forward, I am too lazy to type, I will just quote the book Fetter 1971: Up to here everything is very straight forward, in particular, since we are working on free electron gas, ##E=\hbar \omega## However, I have no idea how to arrive...

This is actually a two-part question: 1) According to the Copenhagen Interpretation, atoms have energy bands but there's no explanation of how these bands are derived, or why they only form for protons/antiprotons. Any thoughts? 2) The Copenhagen Interpretation mentions that when an atom's...

In the picture below we have two identical orbitals A and B and the system has left-right symmetry. I use the notation ##|n_{A \uparrow}, n_{A \downarrow},n_{B \uparrow},n_{B \downarrow}>## which for example ##n_{A \uparrow}## indicates the number of spin-up electrons in the orbital A. I would...

I am struggling with how to go about this; in particular, I'm not sure I understand what state is being alluded to when Ballentine says "For an electron that approaches the surface from the interior, with momentum ##\hbar k## in the positive ##x## direction, calculate the probability that it...

I did some research online and found that "When certain elementary particles move through a magnetic field, they are deflected in a manner that suggests they have the properties of little magnets." To explain this phenomenon, physicists invented the concept of spin. So far so good. What I...

Stationary solutions to the Schrödinger equation factor into a spatial part, e.g. atomic and molecular orbitals, and a temporal part that gives the phase rotation frequency. It is often assumed that adding a constant to the potential leaves the physics unchanged. And clearly, any "spectroscopic"...

Hello, I've seen in a few books on solid state physics that one can deduce an expression for average K.E.: $$<\:K.E.>\:=E_c+3/2\:k_B\:T$$ from the following: $$<\:K.E.>\:=\:\frac{\int \:\left(E-E_c\right)g\left(E\right)f\left(E\right)dE}{\int \:g\left(E\right)f\left(E\right)dE}$$ I can't...

I'm reading through Hohenberg's seminal paper titled: "Inhomogeneous Electron Gas" that help lay the foundation for what we know of as Density Functional Theory (DFT) by proving the existence of a universal functional that exactly matches the ground-state energy of a system with a given...

Since there is only one excited electron, it could come from n=3 to n =1directly or n=3 to n =2 and then n=2 to =1. Hence, there could be one or two lines depending upon the path taken by electron. Is this right?

When I try P_rel_e = P_ideal I couldn't get a single number that is close to the given T_Max. It might be that I used the wrong equations but I am not sure. Can anyone give me some guidence on this question?

Schrodinger’s original interpretation of the wavefunction was that it represented a smeared out charge density however this was replaced with Max Born’s probability interpretation. The issue was from what I understand that a charge density would repel and have self interactions as all the charge...

The proton and electron are described by separate wavefunctions. When they come together in the hydrogen atom are they quantum entangled and have a joint wavefunction.

For part (a) of this problem, The solution is, However, why did they need to take the absolute value of the charge? I thought they could keep the original signs as shown below: Using energy conservation, the electric force dose internal work transferring electric potential energy into...

TL;DR Summary: I have a small nut tied to a string. I take a straw and generate free electrons on it by a handkerchief. Then I thouch the nut with the straw and the nut is to be repulsed by it, because of a transfer of part of its electrons. But it does not happen, the nut is attracted to a...

I have seen many tutorials that provide steps how to transcribe a Feynman diagram into algebra, for instance [here]: However, I have never seen the final line of the calculation converted into a real number. What are the steps to get from the algebra equations transcribed using the Feynman...

what will happend if I keep giving the same amount of energy, constant in time to an electron? Will it stay at the exited state forever

Hi, I asked this question elsewhere, but I didn't understand the answer. It seems to be easy to understand, but for some reason I'm really confuse. I'm not sure how to find the average position of an electron and the average separation of an electron and his proton in a hydrogen atom. To be...

I read something about accelerators using nanotubes. I am a little concerned about the design mentioned in the "High Density with Perpendicular Carbon Nanotubes" part of this paper(https://doi.org/10.3390/photonics8060216). Can wakefield acceleration be done in an electron field? Or maybe I...

As QP says it is uncertain that where you found electron. But its not the same phenomena that one fan blade running so fast that you cant see where the blade is. You can only see the blade on a particular position if you use high resulation camera and its position depend on when you take the...

I have a nanoparticle of cadmium selenide with a diameter d. When it emits a photon with a wavelenght lambda, it happens because an electron jumps from the conduction band to the occupied band across a forbidden band. I can suppose that jump as a jump from a higher energy level (the conduction...

I was reading Feynman's lecture on the double-slit experiment, the attempts to determine which slit an electron passes through. https://www.feynmanlectures.caltech.edu/III_01.html#Ch1-S6 And the key part is when Feynman says, "Then a terrible thing happens.", about the low optical resolutions...

When a photon is absorbed, electrons move from a lower energy level to a higher energy level, so my answer is a, b, c, and f. I don't understand why the solution is b, c, d, e. Can electrons in this case move from a higher to lower energy level? Thank you.

Hello guys, I don't know if this is the right place to ask, so please be kind :/ I have a question regarding the location of an electron that belongs to an atom. A teacher told me that the probability of an electron to be found within its orbital is around 99%. When I asked about the remaining...

Hi everyone! I need some help in a specific task. It´s about this problem: An excited state of atomic calcium has the electron configuration 1s 2 2s 2 2p6 3s 2 3p6 3d1 4f 1 . (a) Derive all the term symbols (with the appropriate specifications of S, L, and J) for the electron configuration. (b)...

Compact electron accelerator reaches new speeds with nothing but light https://phys.org/news/2022-09-compact-electron.html Multi-GeV Electron Bunches from an All-Optical Laser Wakefield Accelerator Abstract We present the first demonstration of multi-GeV laser...

Hi, I am have trouble finding whether or not the topic is possible. It concerns an electronic dipole. I am well familiar with the general rules: https://en.wikipedia.org/wiki/Selection_rule Is it possible for transitions to occur from e.g. ^4P_1/2 and ^4P_2/3, which are both in n=3? If they...

Is this known in QFT or is this "spontaneous".

I can't solve the following exercise: Assume for a certain non-degenerate semiconductor sampe at T = 300 K an intrinsic carrier concentration ##n_i = 2 \cdot 10^{13} \frac{1}{cm^3}## and the band effective densities of states ##N_C = N_V = 10^{19} \frac{1}{cm^3}##. 1. Determine the electron and...

First Assume the following basic circuit: I read in many textbooks that the electrons in the circuit are accelerated by the positive voltage and decelerated by the collisions, so the speed is constant. We also know that the circuit current is I = 10A so the power consumed is P = V * I = 100W...

Not sure if this belongs in Chemistry or Physics. Even less sure if I understand the selection rules for electron transition correctly; hence this question. So I would be grateful for someone to please correct the following: Letting n and m be energy levels An electron that absorbs a photon...

Researchers at the Center of Excellence for Quantum Computation and Communication Technology released a study published by Nature describing a quantum device that models the motion of electrons in Polyacetylene. The device is not a general purpose quantum processor, but the methods they used...

In electron capture, a proton turns into a neutron and a neutrino is emitted. Is (without counting the mass difference between neutron and proton and the mass of the neutrino) the mass of the electron converted into energy in the form of gamma radiation?

If we had a system of ##N## non – interacting electrons than a wavefunction of such a system is a product of one-electron wavefunctions otherwise known as a Hartree product: $$ \Psi(x_1,x_2,...,x_N) = \prod_{n=1}^N \psi(x_n) $$ This means that in such a hypothetical system , it is possible to...

At what point does the electron become ionized in the hydrogen atom solution

I am having trouble understanding this derivation and need some guidance. 1) I tried solving the algebra from the first equation to the second equation circled in red. Can someone please help with what algebra steps, I cannot solve to the circled solution. 2) What does Ee stand for? Is it...

Hi, I would like to ask question about atmospheric electron neutrinos. It is known that atmospheric electron neutrinos originate from the decay of muon in the atmosphere, but we can also calculate that muon with energy more than 10 GeV is able to penetrate about 100 km, so it does not decay and...

Does electron beam in empty space generate magnetic fields around them just as with current in conductor. If yes, then is it experimentally proven that two parallel electron beam would attract each other.

I am trying to compute the Peebles equation as found here: I am doing so in Python and the following is my attempt: However, I'm unable to solve it. Either my solver is not enough, or I have wrongly done the function for calculating the Equation. # imports from scipy.optimize import fsolve...

When an electron flows through a circuit say 250V, does it mean the electron possesses 250eV at any time or does it give out a total of 250eV

For this problem, Is it as simple as using the probability density function, P = Ψ2 and plugging in the radius value given to me? So essentially I am just squaring the wave function and plugging in?

I'm trying to figure out the second order extension of the "trick" used on page 92 (https://www.damtp.cam.ac.uk/user/tong/aqm/solid3.pdf) for the calculation of the effective mass matrix ##m^{\star}_{ij} = \hbar^2 (\partial^2 E/ \partial k_i \partial k_j)^{-1}## on page 94. I think for this one...

Hello there, i wanted to ask if anyone knows a process or mechanism, that reduces the electric field that is requiered to tunnel an electron. When i use the work function of 4 eV (Aluminum) i get with Schottky-Nordheim approach a field of 870 kV/mm to tunnel an electron. Measurements tho just...

[Mentor Note -- Two threads started by partners in a class have been merged into this one thread, since they are working on a shared solution to turn in]

Good day, all I am familiar with both of terms that I speak of in title. But I cannot find a full answer, so I might as well ask the PhD'ers here. What is really happening in Zener and Avalanche breakdown? I have read Guide to Zener Effect and Avalanche Effect and still feel confused. And yes I...

The EM field seems to be required for for local gauge symmetry of the electron matter field under local phase variation. Following is a description (not my verbiage): There is a symmetry in physics which we might call the Local Phase Symmetry in quantum mechanics. In this symmetry we change...

Hello everyone, I am looking for a simple intuitive explenation why the disociation rate is proportional to current^(N) where N determines the N-electron process in Fig. 4 of this article: B. C. Stipe, M. A. Rezaei, W. Ho, S. Gao, M. Persson, and B. I. Lundqvist, Phys. Rev. Lett. 78, 4410...

Here I was going to use ##\int \vec F \cdot d\vec l = \frac{1}{2}mu^2## What I got that is ##l=\frac{mu^2}{2eE}##. Here the question is what is ##l## (I took ##x## while doing the work but here I used ##l## instead of ##x##)? I was assuming that it's ##x## since I am calculating work in the...

When I try following numbers from internet then I don't get an expected answer. ## \mu_0 = 1.25663706 × 10-6 m kg s^{-2} A^{-2}## ##q =1.60217662 × 10^{-19} coulombs ## ##r=2.82x10^{-15} m## Velocity of that electron is given in question ##\vec v= 2 \times 10^6 \\ \mathrm{ms^{-1}}##Since...