The electron is a subatomic particle, symbol e− or β−, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry and thermal conductivity, and they also participate in gravitational, electromagnetic and weak interactions. Since an electron has charge, it has a surrounding electric field, and if that electron is moving relative to an observer, said observer will observe it to generate a magnetic field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law. Electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields. Special telescopes can detect electron plasma in outer space. Electrons are involved in many applications such as tribology or frictional charging, electrolysis, electrochemistry, battery technologies, electronics, welding, cathode ray tubes, photoelectricity, photovoltaic solar panels, electron microscopes, radiation therapy, lasers, gaseous ionization detectors and particle accelerators.
Interactions involving electrons with other subatomic particles are of interest in fields such as chemistry and nuclear physics. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms. Ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge 'electron' in 1891, and J. J. Thomson and his team of British physicists identified it as a particle in 1897 during the cathode ray tube experiment. Electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. The antiparticle of the electron is called the positron; it is identical to the electron except that it carries electrical charge of the opposite sign. When an electron collides with a positron, both particles can be annihilated, producing gamma ray photons.
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...
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...
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...
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...
Hello,
I would like to discuss with my students the deflection of electrons in electric and magnetic fields. For this purpose, I would like to perform the experiments with electron beam deflection tubes and teltron tubes. How would you implement this organizationally in the classroom? There are...
What I did was first noting that ##\hat{\vec{S}}_1\cdot\hat{\vec{S}}_2=\frac{1}{2}(\hat{\vec{S}}^2-\hat{\vec{S}}_1^2-\hat{\vec{S}}_2^2)##, but these operators don't commute with ##\hat{S}_{1_z}## and ##\hat{S}_{2_z}##, this non the decoupled basis ##\ket{s_1,s_2;m_1,m_2}## nor the coupled one...
B equals 50*10^-7 T (at first instance)
Fm equals 8*10^-20 N (at first instance)
I know Fm is perpendicular to the velocity, and I know the estimation of the trajectory (somewhat similar to the curve y=lnx).
Since I think vertical velocity will be constant, only changing the x component, I...
Hello All,
I am aware of databases which list possible gamma-gamma coincidences for desired isotope. For example: here provides a table at the bottom with all possible gamma-gamma coincidence for Co-60.
Question is, are there any similar databases/tables for electron coincidences with...
Imagine a magnet moving up and down so that its flux 'B' cuts the copper rod to produce an alternating emf, suppose if the movement is fast enough such that its frequency equals to the electron spin resonance frequency given by F = B x 2.8 Mhz per gauss, neglecting skin effect, more copper...
I have a question about what happen when an electron in the Bohr model of atom, gains energy because for example is "hitting" by a photon.
Electron have an energy, and it is the sum of potential and kinetic.
When they gain energy, they gain potential energy so they go further away from nucleus...
There is an optimum energy which gives the greatest probability of ionisation of a particular element.
This is said to align with the wavelength of the electron being close to resonances in the atom.
Looking at this in a different way as particles, would it be correct to say that the optimum...
I am very confused on how to go about with this question. The only thing I've tried so far is drawing the fbd of the electron and because of the plates the force applied would cancel which makes it centered between the two plates. As of now that is the only thing I understand, I am not sure how...
If ##\hat{T} = -\frac{\hbar}{2m}\frac{\mathrm{d^2} }{\mathrm{d} x^2}##, then the expectation value of the kinetic energy should be given as:
$$\begin{align*}
\left \langle T \right \rangle &= \int_{0}^{L} \sqrt{\frac{2}{L}} \sin{\left(\frac{\pi x}{L}\right)}...
Hi!
I'm playing around with a type of electron (and by electron/molecule interactions: ion) source that was briefly touched upon in the 1960's.
The basic idea is to use a channel electron multiplier "channeltron" with the anode removed; similar to a single MCP channel. The burst of electrons...
In quantum mechanics it is impossible to prepare an electron in a state where both position and momentum are known with arbitrary accuracy. In classical physics such states do exist, but can they be prepared?
If we assume that the electron is a classical particle (small ball of charge) can we...
Was there any study of this experiment in the context of classical electromagnetism? It is often claimed that such an experiment is impossible to explain classically, yet, the only classical model I've seen employed is Newtonian mechanics (bullets).
The EM fields associated with the electrons...
Hi all,
Why not build an electron rocket? Why won't this idea work? Seems like someone could just hitch an electron gun onto a spaceship. Boom! Electron Rocket.
I was thinking about ion thrusters. These use ions to achieve thrust. They are problematic for achieving a high delta V because...
I had two questions in the field of physics:
We know that in quantum mechanics there is an electron in a certain distance from the distance to the nucleus as a cloud or a cover. But is motion for the cloud defined by the electron moving around the nucleus?
And the main question is, can the...
I'm looking for a good derivation of the "wave" patterns in this experiment. I suppose that if wave-particle duality is an obsolete idea, there must be a derivation from quantum mechanics that gets close results.
Thanks in advance
Hello,
If I understand it correctly, the samples are grounded inside a scanning electron microscope (SEM) to avoid charge build up through the electron beam. Also the non-conductive are coated with a conductive layer, so they can be grounded as well.
However, I do not know how the charge build...
What is the quantum spin of the valence electron in the silver atom in
the furnace in the Stern-Gerlach experiment?
. Up, down, at random, alternating, in a (quantum) superposition (of
both), or none? Does it even have/get one until it's measured/observed
/needed?
. Does the second electron, in...
Hi,
It's not homework but I still thought I better post it here.
Please have a look on the attachment. For hi-resolution copy, please use this link: https://imagizer.imageshack.com/img922/7840/CL6Ceq.jpg
I think in equations labelled "12", 'e' is electric charge and Ex is the amplitude of...
The given diagram looks something like this:
Electric force on nucleus from external field must balance attraction force from electron cloud and electric force from external field.
$$e\vec{E}=\frac{k(\frac{L^3}{R^3}e)}{L^2}\hat{L}$$ where ##\vec{L}## is from center of electron cloud to...