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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When electrons move regardless of what the voltage is, is the strength of the magnetic field a constant?

When electrons move regardless of the what the voltage is, is the strength of the magnetic field a constant? My understanding of the ammeter is the magnetic field of the moving electron effectively ...
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Experimental arrangement of photo current

In my book it say that between the cathode and anode there exist number of electrons which make the space charge. When light falls on cathode photoelectrons are released but is repelled by the space ...
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4answers
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Can we say with certainty whether an electron is a particle or a wave?

I read in my physics book (NCERT class 11, page no. 374) that overlapping waves algebraically add to give a resultant wave and it is also mentioned that this superposition principle implies that the ...
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Do holes flow in a conductor?

I want to if holes flow in a conductor and, if yes, why. What happens when holes reach the end of the semiconductor?
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When stops secondary emission of electrons?

Suppose we have a dielectric sphere immersed in a plasma and initially it is positively charged such that the energy of the electrons in the plasma is sufficient to hit the sphere and begin with the ...
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483 views

How do you measure the mass of the electron very precisely?

This week I showed my high school students that if you add the mass of a proton and the mass of an electron the result is higher than the mass of a hydrogen atom, because of the binding energy being ...
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Can we uniquely determine the particles emitted in a neutron induced binary fission of a radioactive element?

Can we uniquely determine the particles emitted in a neutron induced binary fission of a radioactive element? For example, if we have $ \newcommand{\U}{\mathrm U} \newcommand{\Mo}{\mathrm{Mo}} \...
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How is it possible that the wave of an electron (a particle with mass) with shorter wavelenghth has a faster phase velocity?

How is it possible that the wave of an electron (a particle with mass) with a shorter wavelenghth has a faster phase velocity? Does omega (angular frequency) grow faster than k (wave number)? Does it ...
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Work Function of metallic ions

How does the work function of a metal change from when it is engaged with other metals in metallic bonding on the surface compared to when it is engaged in in a coordinate bond, such as an iron ...
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In what directions do a photon and an electron move after they collide?

Suppose a billiard ball moves in a straight line and the center of another billiard ball is at a distance from that line of less than the radius of a billiard ball. That distance determines which ...
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Why are atoms stable? [closed]

I will ask my question in a way that's all handwaving and no math, and I will welcome handwaving answers. I'm interested in visualizing the concepts. A long time ago we had an idea about the atom as a ...
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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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Physics history — the Ultraviolet Catastrophe [duplicate]

I will ask my question in a way that's all handwaving and no math, and I will welcome handwaving answers. I'm interested in visualizing the concepts. We had an idea about the atom as a massive nucleus ...
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521 views

Can an electron have an electric quadrupole moment?

There are several groups actively working to measure the electric dipole moment of the electron. Is it possible for the electron to have higher order multipole moments, like quadrupole? The reason ...
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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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Trying to understand electron diffraction

I'm trying to understand how electron diffraction works, but I'm not really getting it. Here's an image Here are a couple of questions about it that I can't figure out. Why is the angle of the beam $...
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Can the Mikheyev-Smirnov-Wolfenstein (MSW) effect be modified by non-standard neutrino-neutrino interactions?

The MSW effect describes how propagation of neutrinos through matter can resonantly enhance the neutrino mixing. The reason for this enhancement is that the presence of electrons in matter changes the ...
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If the Landé $g$-factor of an electron is its magnetic moment due to its inherent quantum spin, and its spin is its magnetic moment, why isn't it 1? [duplicate]

I was taught that the 'spin' of an elementary particle was its inherent, unalterable magnetic moment due to its physical spin, or angular momentum, that may or may not actually exist. Therefore, if ...
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What are electrons holes and how they differ from free electrons?

So I'm confused about electrons holes and how they differ from free electrons. I have this question in my mind for months and I couldn't any solid answer.
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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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1answer
312 views

Point particle with a magnetic dipole?

I have read these questions: Are contravariant basis vectors and basis 1-forms identical? Where John Rennie's answer says that electrons do have an electric dipole moment and we imagine that in math ...
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388 views

How do you fit a dipole in an electron?

Experiments used to observe particle spin properties (such as Stern-Gerlach) rely on a varied magnetic field and a dipole-like reaction in the particle, deflecting it in one direction or another. In ...
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1answer
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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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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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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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How is energy conserved in spontaneous emission?

I was reading through the section on spontaneous emission in Introduction to Quantum Mechanics (2nd Ed.) by Griffiths. In section 9.2.2 he explained that spontaneous emission is really a stimulated ...
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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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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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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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Why doesn't a chemical reaction occur with the movement of electrons in the context of electricity?

In school it is generally taught that the movement of electrons between two atoms causes a chemical reaction. However, when it comes to electricity why doesn't a chemical reaction occur with the ...
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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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Stacking batteries and electron flow

About Fuel Cells and Batteries: I understand the analogue with increased water height as two cells (battery or fuel) are connected in series. However if we for instance have two batteries contected in ...
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Energy of electron [closed]

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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2answers
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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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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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342 views

Amount of free electrons in a metal

How can I calculate the amount of free electrons in a metal? I search the forum but found nothing What I want to know is how many electrons can I remove from a metal using photoelectric effect (...
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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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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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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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1answer
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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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Diffusion vacuum pump plans [closed]

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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1answer
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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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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 are resistivity and tunneling related?

If we consider a sandwich with three nanometric layers: conductor-insulator-conductor and apply voltage (lower than breakdown voltage) from both sides tunneling will occur. Is tunneling dependent on ...
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1answer
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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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1answer
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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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