Questions tagged [electrons]

Negatively charged particle with spin 1/2. A component of mundane terrestrial matter, and part of all neutral atoms and molecules. It has a mass about 1/1800 that of a proton. Its antiparticle is the positron.

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If the electron were not precessing would its spin along $z$ be $√3/2$ instead $1/2$? [closed]

If the electron were not precessing would its spin along z be √3/2 instead 1/2 as the number √3/2 is the total spin which is somehow shared by x,y and z axis? Should this precession causing an ...
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Why are electrons inherently magnetic? [duplicate]

I read that permanent magnetism is caused by electrons orbiting in a way which produces a net magnetic field. but how can a particle with no dimensions have a magnetic dipole? also I read that photons ...
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How does a generator generate electricity in microscopic terms of the electrons flowing?

To my understanding, you need a rotating/changing magnetic field to create an electrical current flowing through a wire, but how are the electrons traveling through thin air to move into the wire and ...
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Can we fully ionize an atom by annhilating its electrons with a positron beam?

I am unable to digest research papers on this topic so I am asking here. Can an atom be fully ionized by a positron beam through positron-electron annhilation? What are the limitations of this process ...
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De Broglie wavelength for electron and muon

Given a 100 eV electron, I have to find its De Broglie wavelength. I do this by finding its momentum $p=\sqrt{2m_eE}$ and then using $\lambda=\frac{h}{p}$. I then wanted to repeat the same procedure ...
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Two opposing factors regarding the potential energy of an atomic system

First, let me establish what I know and what confuses me about the topic to begin with, before posing the question at-hand: The potential energy of an electron increases the further from the nucleus ...
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Why does my TV screen stay dust-free while other screens do not?

Recently I bought a pretty cheap flat-screen TV. Screen is IPS, semi-matte. 7 months now, I haven't cleaned it once, no dust at all. The TV works a few hours per day. I was wondering why it does not ...
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What is the difference between two plane waves with positive frequency?

Is it possible to interpret the first plane wave $e^{(ikx-iωt)}$ as an electron and the second plane wave $e^{(-ikx-iωt)}$ as a positron? I ask because they both have positive frequency (energy), but ...
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Energy of electron

If we have a reservoir of negative charges and we bring a test charge (electron) near that reservoir. Will all the potential energy of that test particle will be converted to the kinetic energy of the ...
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How does the difference between electron flow and conventional flow NOT make a difference?

I keep hearing that it doesn't matter whether we use electron flow or conventional flow for direction of current for simple circuits like those taught in introductory electrical circuitry classes. And ...
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In a solar cell when an electron is freed due to light in the depletion layer, why does it move to N-type layer even though it is negatively charged?

Even though in a solar cell the N-type layer is negatively charged why do the electrons from the depletion layer get attracted to it?
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How much $GeV/{c^2}$ is 0.51099895000 $MeV$? [closed]

I want to know mass of an electron in $GeV/{c^2}$. I am a high school student so not familiar with these kind of particle physics unit so I am slightly confused. It would be great if you would tell ...
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Field effect electron gun at positive potential in the cathode and anode

Suppose a field effect electron gun emits electrons if the cathode is at 0V and the anode at 12V, in such a way that the potential difference is 12V, what happens if the cathode is at 500V and the ...
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Is there actually current flow around an atom?

The classical model of the moment of a loop of current, which is $\mu = I A$, where A is the loop area. I'm in an introductory E&M course where the moment of an atom is modeled using this simple ...
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Electron double slit thought experiment

If you do an electron double slit experiment (with one electron at a time), you get an interference pattern as usual. I am wondering what would happen if you scattered a photon (with a given energy) ...
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How do you derive that $v= 2W/QI$?

I was searching for the derivation of the mass by charge ratio of the electron and found this as part of it. Here $N=$ no. of electrons, $v$ is the velocity of the electron, $W$ is the work done in ...
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Diffusion vacuum pump plans

I found some plans of diffusion vacuum pump. I want to ask you if vacuum pump in this plans can work properly or thease plans are only some sketches from research which are not useable. I found one ...
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Derivation of the radial Hartree-Fock equations

Can anyone help deriving the radial Hartree-Fock equations of atoms from the Hartree-Fock equations $$(h_i + J_i - K_i) \psi_i = E_i \psi_i$$ where each orbital $\psi_i$ involves three space ...
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Field positive ion emission

A metal is approximately a sea of mobile electrons and a lattice of positive ions. In a vacuum, a piece of metal with enough negative charge will release electrons. Sharp points enhance this effect. ...
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Ionization energy meaning in terms of Bohr model

Ionization energy means the energy required to remove an electron from the valence shell of an atom. Now Bohr did believe in orbits, so what does ionization energy mean in the Bohr model? I understand ...
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Need help in clarifying my understanding regarding absorption and emission spectrum

In absorption spectrum . So , what happens here is that when white light is passed through a gas. The photons of the white light are absorbed by the electron in the gas. This means that the electron ...
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Why do we set the number of degrees of freedom of an electron in a gas to 2 rather than 3?

I was reading up on basic properties of plasmas and came across this description in the Wikipedia on how to convert between eV and Kelvin units to describe the amount of energy of the electrons: The ...
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How does an atom for non-metals look like?

Here, I have drawn a orbit. Now, what I have studied in this atomic structure for non metals is that electron are present in orbitals. So, I have drawn them with yellow colour. Also, they (Online and ...
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Were electrons initially left-handed, as neutrinos still are today?

These days, neutrinos are left-handed, just as they were a long time ago. These days electrons are right- as well as left-handed. Were they only left-handed a long time ago, before having interacted ...
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What is an example of an electron acting as a particle? [closed]

I'm aware that, like all quantum objects (I think), an electron can act as both a wave and a particle. Electron diffraction is a good example of how an electron can act as a wave, but I'm struggling ...
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Why doesn't the length of a wire directly affect potential difference in a circuit?

I am currently in a Physics II course and we learned about the potential difference between two points in space that are a certain distance away from a point charge. If the distance is directly ...
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Forming of helium in radioactive decay

I have just came across a question, where 1mole of Uranium (238 92) gets converted to Pb(206 82) now after balancing we get that during this decay in presence of air, 8 alpha particles and 6 beta ...
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If electrons can be created and destroyed, then why can't charges be created or destroyed? [duplicate]

I read on Wikipedia that electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. Also, that they can be ...
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In a synchrotron, do electrons make periodic recoils?

Synchrotron radiation happens because circular motion of electrons produce a tangential acceleration-- or something along those lines. Point is, photons are produced by these accelerated electrons. As ...
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When a long wave photon is emitted by an electron, how come it is perfectly symetrical?

A long-wavelength, e.g. radio frequencies, of say, 1 km, has a period lasting about 1/300000th of a second. So for an imaginary fixed observer watching the incoming wave, it takes some time to go from ...
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What is the distribution of photon frequencies emitted by an antenna powered by AC?

This is a follow up on answer by Holger Fiedler here: https://physics.stackexchange.com/a/622802/230132 He writes that an antenna powered by alternative current (AC) will emit other frequencies than ...
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Selection rules for electronic transitions in dipole approximation

I saw this video which provides a clear, though simple, introduction to the argument. I think the main thing missing is a proof for: $\Delta \ell = \pm 1 $ $\Delta m_\ell = 0, \pm 1$ $\Delta m_s = 0$...
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What is the most correct way to think about electrons? [closed]

I'm sorry for this question, I know it's been asked before What is an Electron? but the answer doesn't really help me.. Studying chemistry the teacher tried to explain what atoms are, what electrons ...
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Different drift velocities and their effect on the velocity of associated magnetic fields

If in a long conductor one had a large diameter copper wired going to a smaller diameter copper wire of half its diameter then the drift velocity of electrons would speed up at the junction to the ...
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If ordinary electron microscopes have wavelengths 5,000 times or more shorter than visible light, why can't they see atoms?

Electron microscopes can easily 'see' down to .1 nanometers (1 ångstrom) or less, correct? And a single hydrogen atom, in its ground state, is about .106 nanometers (Bohr diameter) wide, right? So ...
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Can a group of electrons act as one and deflect a photon as a group?

There are interactions between electrons and photons. But do they always happen on a one-to-one basis? Or can an ensemble of electrons act as a single entity? Especially, are there parts of the ...
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How can an electron's de Broglie wavelength be LONGER than .0024264 nanometers?

If the rest mass of an electron is about 510,998.5 ev, or .5109985 Mev, doesn't that mean that even the slowest-moving electron has a wavelength of no more than .0024264 nanons? That is the wavelength ...
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What is the difference between areal density and attenuation coefficient?

Speaking of beta electrons, their attenuation is usually described by the areal density $\sigma$, i.e. "how much" g/cm^2 of a certain material they can pass through before stopping. I've ...
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Radiation attenuation parameters for beta and gamma rays

I know that to describe the attenuation radiation undergoes while passing through a material, we use the areal density (which is basically the penetration depth * density of the material) for beta ...
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Calculating the electron orbital for the following (4, 1, -1, -1/2) [closed]

I'm fairly new to applications in physics, so would really appreciate your support on whether I performed the following calculation for this orbital correctly. Also, what does it mean when $\pm\frac{1}...
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Photon hits an electron perpendicular to its velocity, Relativity and Work?

In the phenomenon of the Compton scattering a photon can hit a free electron under any angle. The photon can be regarded as a 'complex' of two photons one along the velocity v of the electron and ...
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Applying the creation operator twice

Consider the electron field in quantum field theory (or the electromagnetic field if easier). My understanding is that what we call an electron is the result of applying the creation operator to the ...
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What are the operators associated to the electron/electromagnetic quantum field?

After reading through a number of questions on SE including What are field quanta? and What are quantum fields mathematically?, I am still struggling with what specific operators are associated to ...
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Is electron a matter?

I know electrons are subatomic particle which makes up atom the building block of matter. But is electron a matter itself? More over is atom or quantum particles matter too considering their particle ...
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Finding distance of closest approach of an electron to an infinite line [duplicate]

The initial distance from the line is available with all necessary information to come up with a formula. How would I get started with this.
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Does a positron go into decay process like some other elementary particles ? Electron, it's counterpart is stable and has a long half life

Can a positron decay? Or is it a stable particle like its counterpart the electron? (Reference: https://physics.aps.org/articles/v8/s138)
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What happens to the charges when a resistor is short-circuited?

let's consider a parallel between a short circuit and a resistor $R$, supplied by a voltage source $V_S$ with a series resistor $R_S$. Circuit Theory description: the resistor $R$ is completely ...
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Relation between electrons inelastically scattered and penetration depth

I am trying to find out the relation between the number of electrons inelastically scattered (or rather mostly plasmons) and the penetration depth of the electrons in the sample. The function should ...
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Can you ionise air via thermionic emission of electrons?

Assuming air is made up only of 78% $N_2$ and 22% $O_2$, what percentage of the $N_2$ and $O_2$ would gain a negative charge if held in a container with a high density of free electrons?
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How to understand the derivation of thermally averaged cross sections?

$$ \frac{d\langle\sigma_\text{ion}^{nl} v\rangle}{d\ln E_\text{er}}=\frac{\bar\sigma_e}{8\mu^2_{\chi e}}\int q|f_\text{ion}^{nl}(k',q)|^2|F_\text{DM}(q)|^2\eta(v_\text{min})\ dq $$ How do I understand ...

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