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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What's a normalized coupling strength?

While reading about elctron-phonon coupling, I came across the term normalized coupling strength. It was defined as $$\eta = g / \omega$$ where $g$ is the coupling constant and $\omega$ the ground ...
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Fermi Gas - Number of Free Electrons at High Temperatures

What I am trying to do is to compute the specific heat of a free electron gas in a conducting metal. I am using Fermi-Dirac statistics as my framework to build off of. Importantly though, I want to ...
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When does an electron release energy as photon and when as heat?

Suppose we have a compound which has been given energy(either in the from of heat or light). Now, its electrons would absorb this energy and kick up to a high energy level. But, it would also re-emit ...
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Davisson and Germer experiment

I was reading about the experiment that confirms the wave particle duality as we see a sudden rise in galvanometer which was explained as a phenomenon of constructive interference. Is it possible that ...
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What is the evidence (experimental observation) that elementary particles have spin angular momentum?

From what I have read here, the concept of spin is attributed to a calculation based on a mathematical model using quantum mechanics. For example, How can a particle with no size have angular momentum?...
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An electron has no known internal structure, does that imply it has an unknown one?

I'm currently reading Alonso and Finn's Electromagnetism book. It explains that the spin contributes to the magnetic moment and is somewhat comparable to a rotation of the particle around its own ...
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What would a large imbalance of protons and electrons actually do?

Over on worldbuild.se there have occasionally been questions where the answer is that there would be a sudden large imbalance between the number of protons and electrons. The answers have also stated ...
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In the stern-Gerlach experiement how do we know that the magnets don't change orientation of the electrons to up or down?

I watched this video: https://www.youtube.com/watch?v=rg4Fnag4V-E Say the electron's north pole started off 60 degrees from the south pole, since the electron has little mass wouldn't that make it ...
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How do electrons in metals manage to have zero acceleration in constant $E$ field (as in a DC circuit)?

From Newton's second law, a charged particle driven by a constant electric field should move with a constant acceleration. But electrons in a circuit acquire a steady average velocity which gives rise ...
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Entangled Material

Recently I saw the case of creating two entangled electrons with opposite spins from the Higgs boson (which has no spin). The electron spins are always opposite to equal zero as a sum - conserving the ...
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Why do electrons flow in the opposite direction of the electric field?

I was taught that the potential decreases in direction of electric field but when we place a positive charge in between it's electric field is too in that same direction but the negative charge has ...
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Deflection of an electron from a charged wire and from an interference grid: In both cases the electron radiates?

Near a charged wire a moving electron is deflected. Since the deflection is an acceleration, the electrons emit photons. What about an electron's radiation, which is affected by an interference ...
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Emission of radiation by a charged particle undergoing acceleration [closed]

An electron is travelling along the x-axis. It then changes its direction by 45 degrees. Will it emit an electromagnetic wave?
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In an electron beam in the atmosphere, is the light region of the beam under low pressure compared to atmospheric pressure?

In an electron beam, is the light region under pressure below atmospheric pressure? Motivation of my question: In the cathode ray tube, the cathode ray (electron beam) becomes luminous and visible ...
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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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Binding energy for electrons

When protons and neutrons interact attractively and coalesce to form an atomic nucleus, their energy in this state must be less than what it was when they are separated, so they lose mass which is ...
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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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How do you get max kinetic energy from photons hitting electrons?

I read if you increase the frequency then you can get the max kinetic energy and if you decrease the wavelengths you can get enough energy to knock the electron out of its atom of a gas. Is this true? ...
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Has the ballistic motion of an electron in gravitational field ever been measured?

Reading this question I thought of an argument that an electron's trajectory would bend in the gravitational field despite the electron's being incapable of strong interaction; this would then ...
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Is potential Difference Really a Measure of Electromotive force?

If I separate some amount of positive and negative charge a certain distance I will create some voltage. If I then separate the same amount of positive and negative charge a longer distance I will ...
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Solenoid and induced electric fields

Let us suppose there is a solenoid which has $n$ turns per unit length the current is varying with time as $I =kt$ where k is a constant if the current is flowing then there must be induced electric ...
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Measuring electron spin

How do experimental physicists measure the angular momentum for the spin of an electron? A paper about an experiment would be helpful. Alternatively, how was the electron spin value of $\hbar/2$ ...
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Dirac's Principles of Quantum Mechanics, Electron Spin

In Section 37 (The spin of the electron), Dirac writes, "The eigenvalues of $m_z$ are $\hbar/2$ and $-\hbar/2$, so the eigenvalues of $\sigma_z$ are 1 and -1, and $\sigma_z^2$ has just the one ...
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Internal energy of free two-dimensional electron gas

In our lecture, we had the following scenario: Suppose we have a 2D-free electron gas which is in a magnetic field $B$ perpendicular to the free electron system. Now the electron states have energies ...
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Photoelectric effect, work function and Kinetic energy range

In the photoelectric effect, why do emitted electrons have a range of kinetic energies? Is some energy just lost as heat when it is released from the surface of a metal and if so, why don't all the ...
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What is meant by the “lowest energy state” of an atom?

What do people mean when they say that when an atom has a full outer shell, it is in its "lowest energy state" and that this is the most "stable" configuration (thus it is not ...
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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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Is electricity really the flow of electrons or is it more involved?

I am new to the physics category of the Stack Exchange site. I apologize if my question is wrong, too broad, simple, or worded incorrectly. I am just trying to figure out what is true and false when ...
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In metals the conductivity decreases with increasing temperature?

I am currently studying Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light, 7th edition, by Max Born and Emil Wolf. Chapter 1.1.2 Material equations ...
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Electron scattering to measure the nuclear radius

I have been taught that you can find out the size of a nucleus of an atom by firing electrons at high velocities at the atom. This causing scattering due the positive charge of the nucleus and ...
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Opacity/transparency of conductive meshes to charged particles (electrons/ions)

When using a conductive (metal) mesh, effectively a metallic woven fabric, in vacuum applications as a "grid" for charged particle optics, how does one calculate (or at least estimate) the opacity or ...
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What are the two elements of the electron field?

I'm not a physicist, I don't know if this will make a lot of sense, so bear with me. I'm just reading about how particles like the photon, electron, graviton, etc are each associated with their own ...
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How do electrons divide?

Electrons show a banded distribution at the end of a double-slit experiment set-up. This banded pattern shows that wave interference prevents many electrons from reaching areas where probability is ...
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Why can electrons excite surface plasmons but not photons?

On optical energy loss function, it is said that we don't see the surface plasmon. However, we can see the plasmon peaks on reflection electron energy loss spectroscopy. My question is that why ...
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Why does not a free electron fall into the nucleus during elastic scattering?

When a free electron finds a hole in the medium, they can re-combine and annihilate each other. So far so good. A free electron can also scatter from positive atomic center (say it elastic scattering ...
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What is thephysical meaning of transport cross-section?

Wikipedia explains the momentum transfer cross-section: https://en.wikipedia.org/wiki/Momentum-transfer_cross_section What is its physical meaning? I interpret it as the displacement rate. For ...
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Is the Dirac-Fock electron density model is the most accurate one?

Salvat, F. et al. (2005) reported numerical Dirac-Fock electron density model provides the most accurate description of the electron density model of a nuclear charge. Why? For example why is that ...
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Current density vector clarification

I have some basic doubts about current density vector $\vec J$, which is defined as "the vector whose magnitude is the electric current density, and whose direction is the same as the motion of ...
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Radius of electron and electrostatic energy [closed]

The classical radius of electron is obtained from the electrostatic energy of a sphere of radius $r_e$ which is: $U=\displaystyle\frac{e^2}{4\pi \epsilon_0r_e}$. For the electrostatic energy of a ...
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How to understand a constant potential in the nearly free electron model?

In the nearly free electron model, we assume that the potential is weak. Now, in a book by Rudolf Gross and Achim Marx, it states: I know that the text is in German, but bear with me: The relevant ...
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Is the Pauli exclusion principle also involved in free electrons?

Imagine I want to make a laser of electrons like a laser of light. Is that possible, or does the Pauli exclusion principle prohibit that?
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Analysing electron diffraction

In analysing photon diffraction by a single slit we add up a series of electric field phasors. Is there a similar method for analysing electron diffraction by a single slit?
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Are two interacting electrons in an isolated system?

From your point of view, two electrons are initially at rest. In time, they repel one another, leading to an increase in both of their kinetic energies. If they are isolated from the rest of the ...
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Electronic component of the Hamiltonian operator and uncertainty principle

This question has to do with the concept of uncertainty principle. The Hamiltonian operator has the electronic component that takes the inverse of the distance between any two electrons. My question ...
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Where are the electrons of a cathode ray tube coming from when using AC?

I see in this picture a beam of electrons leaving the cathode. But I read before, that the electrons can flow out of a copper wire only, if they are replaced by other electrons. I guess, that in the ...
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Is the screen in CRT connected with a positive pole?

I don't understand this passage would you clarify it? "These electrons are then freed (liberated) from the metal and are then picked up by the screen, which is connected to a positive pole called the ...
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What is the exact mechanism of flow of electricity?

When a steady current flows through a conductor, the electrons in it move with a certain average ‘drift speed’. One can calculate this drift speed of electrons for a typical copper wire carrying a ...
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Voltage of a free electron

Every good textbook says that the reduction potentials of half-reactions are all relative. There is no absolute standard, so the conversion between hydrogen gas and aqueous 1M hydrogen ion at a ...
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Why doesn't the magnetic field make electrons escape out of the material?

If a conducting rod moves within a magnetic field, the electrons within it will move for a short amount of time to create a potential difference. When the current is created within this rod, the rod ...
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What happens to an electron in vacuum?

What happens to a free electron in vacuum? Does it accelerate? Does it keep absorbing energy from vacuum fluctuations? Or does it lose all its energy and ceases to be an electron? Please avoid ...

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