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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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How can the velocity of elecrons in graphene be measured?

I'm trying to understand how one can measure the velocity of electrons in graphene, from an experimental point of view. Does anyone have some clue?
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Why cannot electrons be accelerated by cyclotron?

I was reading about cyclotron and it's working. I found out that electrons cannot be accelerated by this device. The reason I found was that they are too light. But I want to know why exactly ...
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Do battery electrons only move if there is a positive terminal at the end of the wire?

I'm sorry if this question may seem wrong in many cases. What would happen if we had a wire with the length of 1 kilometer that connected the two terminals of the battery? Do electrons care if the ...
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Doubt in relation of kinematics and oscillation of electrons [on hold]

My question is about the effect of a radio waves on an Ionospheric Electron. The ionosphere is a region of electrically neutral gas, composed of positively charged ions and negatively charged ...
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Maximum velocity of an electron across a tube with potential [on hold]

Sorry i usually don't ask such fundamental or silly questions but I'm having trouble with this. I'm nearly sure I'm right doing this question based on an x-ray whereby an electron is hypothetically ...
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Diffraction pattern of X-ray and electron

Electron diffraction is used to study about wave - particle duality of matter. A beam of electrons directed at a single crystal produced a diffraction pattern like an X-ray diffraction pattern. I ...
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How can light travelling forward send an electron forward?

Light travels along the x-axis and strikes a stationary free electron. Its E field oscillates along the y-axis. The electron moves off at an angle with respect to the x-axis less than 90 degrees. ...
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Do photons “bounce off” of electrons?

I’ve been reading a book, and in one part the author explains how electrons only absorb the wavelengths of light that can take them to an excited state, i.e. that can take the electrons to a higher ...
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Velocity Selector Question with Unknown Voltage

In a diagram, electrons are emitted from a hot coil with initial velocity 0 at plate A and then pass through a uniform field between two plates (A and B) where $V=1.00\times10^4$ volts. After, they ...
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Joule's heating effect

Can we derive joule heating effect or heating of current using energy conservation for electrons when current is varying with time ?Like using concept of drift velocity,potential diffrence across ...
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Does charging any electrical device in exterme temparature affect the current flow?

Recently in an Electric vehicle(EV) charging station, the charging time to charge a particular vehicle was 1 Hour (18V capacity of battery), but now in temperatures beyond 40 Degree Celsius, it is ...
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The electric and magnetic field, reaching to infinity

I have difficulty’s to accept that the electric and magnetic field components of photons as well as of electrons and the other subatomic particles are extended to infinity. For practical use that does ...
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Why is there no B-field parallel force on an electron orbiting a magnetic field line?

If an orbiting electron creates a toroidal magnetic field like a ring of current does, and this field is oriented opposite to the magnetic field line the electron is orbiting, then why is the electron ...
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Why are there $1 / 1.602176634 \times 10^{-19}$ electrons in a coulomb?

Why that exact number of electrons in one coulomb? who decided it? there is nothing wrong with the number, it just seems slightly messy. Why didn't the scientific community just settle on an easier ...
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What makes a atom more likely to become a cation (lose electron)

What makes an atom more likely to lose an electron and become a cation? Does the exact location of the electrons maybe influence that? I know that you can't know the exact position of an electron ...
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How did scientist get photos of wave function of electron in the double slit experiment?

In the double slit experiment I know that the electron fires as a particle one at a time then splits goes through both slits and recombined and interferes with itself and hit the wall creating a ...
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Why do atoms interact differently? [closed]

We live in a 3-dimensional Universe, so why don't atoms (electrons) follow the same rules as humans, planets and other 3-dimensional objects? So does that mean electrons and other quantum objects pop ...
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How do electrons exit LEDs? Aren't they in the valence energy state?

If a conducting electron reduces to the valence band in an LED, where does it get the energy to go back to the conductance band upon leaving the diode so current can flow? I'm confused as to how ...
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Can electrons fly off a conductor?

This is probably a stupid question, but what if you made an electron flow through a superconductor so that the electrons build up speed flowing through the wire, and then cut the wire. Would the ...
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What is Electron Excitement in the Bohr model?

Is electron excitement the absorption of a photon thereby causing an electron to move to a higher energy level? In my textbooks, electron excitement is implicitly implied to mean that an electron ...
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Do delocalized electrons have different energies?

Consider a molecule with alternating single and double bonds between carbon atoms, such that multiple resonant configurations are possible, e.g. beta-carotene. While using UToko's edx course about ...
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What it means that there is only one electron in universe? [duplicate]

Could someone explain if this statement is and what could possible mean?
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Does a spinning electron stop spinning

An electron caused to spin in a magnetic field gives off synchrotronic radiation (Synchrotron radiation (also known as magnetobremsstrahlung radiation) is the electromagnetic radiation emitted when ...
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Photoelectric effect in space floating metal

I have read this question: Electrical neutrality in photoelectric effect Now the answer by HiddenBabel says: Metals are conductors. As electrons escape, new electrons easily flow from ground ...
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Electrical neutrality in photoelectric effect

In photo electric effect ,if electrons escape, shouldn't that leave the metal positively charged ??. How does it maintain its electrical neutrality ? And if it doesn't , shouldn't the work function ...
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Electron gun design

I have a question about electron guns. I have read a lot, and all designs use high NEGATIVE voltage ($-1000$ V for example). Is possible to use high POSITIVE voltage like this drawing? Or do you think ...
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What would happen if I bring an electron near a conductor

What would happen if I bring an electron near a conductor Charges should be induced, but since a charge cannot be smaller than that of an electron.... Edit :This is not a homework question. I had a ...
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Do Maxwell's equations predict that electrons have no internal structure?

As far as I know, Maxwell's equations can't be derived from anything more fundamental. Does this indicate that electrons have no internal structure? I mean to say that, in my view, the entire nature ...
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What happens when we use Faraday induction on a coil that already carries a current?

Consider the following experiment: (1) Attach a coil to a current meter, and run a magnet over that coil, measuring the current generated. This is ordinary Faraday induction. (2) (i) Attach the coil ...
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Why does decreasing the wavelength of light while maintaining intensity decrease current in photo electric effect [duplicate]

I understand a photon with a smaller wavelength is more energetic so for a given intensity, less photons are incident on the electrons and so less photo electrons reach the detector per second. ...
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Pair production problem, how is energy not conserved here?

The problem is asking me to find the minimum photon energy that would produce an electron-positron pair when it collides with a free electron at rest. This is my attempt at trying to conserve both ...
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Why do electrons revolve around the nucleus? [duplicate]

Why do electrons revolve around the atom's nucleus? Where does it get the energy for the revolution? Do the electrons stop revolving at absolute zero temperatures?
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Can every mass obey the Newton's 3rd law?

As in, if we were able to produce a very huge amount of force on a very small body, would it push back with the same force? Given it doesn't break or disintegrate. Like if we electromagnetically put ...
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Why is the photon emitted from a bound electron dropping energy levels not exactly equal to the difference in energy levels [duplicate]

In a problem sheet there was a question asking us to guess why a photon released from an electron dropping energy levels does not have the exact difference. My guess is that the electron needs some ...
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Absorbing Photons or Re-Emission

When the electron absorbs radiation, it can seemingly do 2 things. Firstly, the electron can become excited and jump to a higher energy level before collapsing and releasing that energy as a photon. ...
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Confusion about electron flow and current

So, I learned in class that current is defined as positive charges moving from south to north. However, in all reality, the negative charges are moving, but the convention of positive to negative wors ...
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Should the mass of the electron be included in the mass of products when calculating mass defect?

In a physics question, I encountered a beta minus decay reaction. If I were to calculate the mass defect, should the mass of the electron be included in the mass of the products?
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Why does the electric flux through the surface of a cube with a point charge inside it remain unchanged when the point charge is moved? [closed]

Why does the electric flux inside a cube remain unchanged when the charge is moved within the cube (not on vertices/faces/edges) but just in volume?
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Lightning in space, would it be a perfectly straight line?

I have read this question: Can lightning happen in a vacuum? I do understand that here on Earth lightning consists of electrons moving in space and some of these electrons are tracing path, and ...
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Electron beam physics

I am looking for good resources to learn about electron beam optics to be able to characterize electron guns.
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What is the most energy efficient source of electrons?

Wanting to build a cathode ray tube, and I see there are a few electron sources such as thermionic emission and field electron emission. Since my project is small scale, since I don't want to go to ...
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Can Compton scattering increase a photon's energy?

I've read (in Hagai Netzer's book The Physics and Evolution of Active Galactic Nuclei) that "Comptonization in the [black hole's accretion] disk atmosphere can increase the energy of some photons..." [...
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Is it possible to create and control a magnetic field in a dielectric material?

A capacitor is usually formed by an insulater between two conductive plates. By applying voltage difference between the plates we create an electric field within the insulator in one direction. If you ...
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Are / Why are the H II regions positively charged?

One of the questions in our recent astrophysics course homework was to find the general opacity $\kappa$ of H II regions. We know that the H II regions are almost entirely ionized hydrogen and I ...
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What came first, neutrons or electrons? [closed]

I wonder if electrons were first (at an early stage of the cosmos) embedded into neutrons, making it easier to understand why they would fit so well with protons later, or if the genesis of electrons ...
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Can free electrons in a cathode ray pair up?

I read Wikipedia articles "Cooper pair" and "Electron pair" among others. In an atom electrons can be in the same orbital only if they have a different spin (Pauli exclusion principle). In Cooper ...
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Faraday cages and what constitutes the minimum number of atoms to build an optical mirror

I recently asked this question: What is the minimum number of metal atoms necessary to make a mirror? However it seems I did not make myself clear enough about what I was looking for, even though the ...
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What are the prerequisites for a free electron and an atom/ion to recombine?

I'm mostly interested about recombination not in plasma (e.g., recombination of beta particles with atoms that they pass by), although the rules are probably the same. Say, there's a free electron ...
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Does wave-particle duality rely on accepting the Copenhagen interpretation?

If you're a scientist that subscribes to the many worlds theorem, does that mean you do not accept wave particle duality? Seeing as MW postulates that the wave or particle form has always existed that ...
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In electrodynamics, why do we say $\mathbf J = \sigma \mathbf E$ and not $\mathbf J = \sigma (\mathbf E + \mathbf v \times \mathbf B)$?

Griffiths notes it's because charges have an extremely low $\mathbf v$, so it's essentially an approximation, but aren't charges meant to be electrons? How can they be moving slowly? I usually think ...