# Tag Info

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The strong interaction that keeps protons together is a different kind of force (the strong nuclear force) which does not affect electrons. Electrons don't feel the strong force. They only feel the electromagnetic force and the left-handed ones also feel the weak nuclear force, which converts electrons into neutrinos. As a result, even if two electrons ...

7

There are two separate issues here (not sure which of the two you mean): The first problem is a severe misconception that is similar to Zeno's paradox of Achilles and the Tortoise: Given a hydrogen atom we have (in principle) an infinite number of shells. However, the gap between the shells gets smaller and smaller. If you would jump from shell to shell, ...

5

First of all, you can't expect to recover general classical mechanics by simply making averages in quantum mechanics. Apart from very special cases, you can recover it only in the limit $\hslash\to 0$. In such limit, something similar of what you expect can be proved. In particular, it holds when considering (squeezed) coherent states $C_{\hslash}(q,\xi)$ ...

5

None of the above. Electrons are negatively charged, always. They do not become positively charged under any circumstances. In DC circuits they flow (or rather 'drift' at about 0.1 mm/s) only in one direction, from the -ve terminal to the +ve. In AC circuits they flow forwards and backwards in the wire, changing direction 50 times per second. They don't ...

4

... an electron is point sized Here you find what John Rennie says about this: Although it's commonly said that fundamental particles are point particles you need to be clear what this means. To measure the size of the particle to within some experimental error d requires the use of a probe with a wavelength of λ=d or less i.e. with an energy of ...

3

In a rechargeable battery, two types of reversible chemical reactions take place: Oxidation reaction: in which a chemical, referred to as the reducing agent ($Re$) is oxidised by donating electrons: $$Re \to Re^{z+} + z e^-$$ Reduction reaction: in which a chemical, referred to as the oxidising agent ($Ox$) is reduced by receiving electrons: Ox + z ...

3

Several questions of this nature were asked the last days. An electron does not orbit the nucleus as a particle. In Quantum Mechanics the electron is represented by a wavefunction, which gives you the probability of measuring something about the electron. This probability is spherically symmetrical in the ground state of hydrogen, for example: it means you ...

3

As regards the first question, if you read this article, it might make the difference between waves and particles clearer. Double Slit Experiment Can absolute zero stop the movement of electrons, or solid electrons like those described above? This is an exerpt from Wikipedia Absolute Zero The laws of thermodynamics dictate that absolute zero ...

3

This is a surprisingly complicated question, and I'm not sure there is a universally accepted answer. To see why this is turn off your magnetic field and give the electron enough velocity to keep it in orbit around the Earth. Now in the Earth frame the electron has a centripetal acceleration of $r\omega^2$ and therefore it should be emitting radiation. ...

3

Cathode Rays First, here's a diagram of a cathode ray tube: Cathode rays were named as such because they were emitted from the negative electrode, or cathode, of a high voltage generator. This was done in a vacuum tube. In the diagram, you can see the cathode, from which the rays (really electrons) were emitted. You can also see a tube that went to a ...

2

Strong interaction refers to a different sense of charge instead of electrostatic charge. At least that is to talk about the most direct use of that interaction. There are much, much weaker corrections that have that as an intermediate interaction (virtual quarks). The joining is Cooper Pairs in superconductors. Look that up to see how it is mediated.

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Would it be like in gas p/T dependence ? No, it is much more complicated than this. How does the refractive index of plasma changes with temperature? This is an extremely complicated question for numerous nuanced reasons, including (in no particular order): Plasmas are often in a collisionless or weakly collisional state, meaning their dynamics are ...

2

Double-Slit Experiment I believe you are describing the double slit experiment with electrons (as opposed to with light). The pattern you are describing is called an interference pattern (much like two pebbles producing ripples in a pond and there are parts where the ripples cancel out). Below is a diagram of the double slit experiment. One way of ...

2

The high voltage causes the gas molecules in the tube to get excited or ionised if the electric field is strong enough. When the excited electrons go back to a lower energy state, they emit photons in the process. The energy of the photons (and therefore colour of light that we see) depends on the energy of the state in which the excited molecule relative ...

1

One more thought, some of the power can be dissipated in transistors because each transistor p-n junction have voltage drop of 0,7V. Even in this case the power $P = U \cdot I_b = 0.7 V \cdot I_b$ of the base current is dissipated into heat. Where else should it go? Most transistors in PCs are MOS-Technology. So they don't need a current to operate. ...

1

To answer this question, you'd have to agree on what model of the electron you're talking about. Quantum mechanical? Classical? Electrons can have force exerted on them by electric fields. If this causes the electron to move, then work is done to it. Thus, energy is transfered "to" the electron.

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I can see some mistakes : "I realized that we must have $|F\rangle=\sum_\alpha\int\;\mathrm{d}\textbf{k}\,\Theta(k_F-k)\,\hat{a}^\dagger_{\textbf{k},\alpha}|0\rangle$" This is wrong : the ground state of an non-interacting fermion gas (Fermi sea) is not some sort of superpositions on the individual $\textbf{k}$ states as you seem to suggest. It has to ...

1

I think you're talking about electron ionization. Yes, there would be a "reaction"...the gas would be ionized. There would be a reaction of the form shown below, where $M$ is a molecule, $e^-$ is the electron, and $M^{+.}$ is the resulting molecular ion. $M + e^- \rightarrow M^{+.} +2e^-$ Hope this helps! More information about electron ionization can be ...

1

The atomic model developed starting from the light spectrum emitted by the hydrogen atom. It was known that hydrogen was one proton and one electron. The Balmer series or Balmer lines in atomic physics, is the designation of one of a set of six named series describing the spectral line emissions of the hydrogen atom. The Balmer series is calculated using ...

1

What would occur if an electron at rest was accelerated to the speed of light? Any charged particle can be accelerated its speed increasing as more energy is supplied, but the limit of the speed is the speed of light. At a Lorentz factor ( = particle energy/rest mass = [104.5 GeV/0.511 MeV]) of over 200,000, LEP still holds the particle accelerator ...

1

Electrons can be accelerated to the speed of light (or practically to the speed of light). If you accelerate electrons to merely 5 MeV the velocity of 0.996 c where c is velocity of light, and yes if they are accelerated to that velocity they will emit gamma like radiation. Here I would like to clarify that the term gamma radiation is mostly used for the ...

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You are confusing the drift velocity of the electrons (which is < 1 mm/sec) with their Fermi velocity (which is $1.57\cdot 10^6 ~\rm{m/s}$ for copper) - source. If any "bunching up" of electrons were to happen, it would very quickly resolve itself. As was pointed out in the comments, the "signal" that travels in an electrical wire is essentially carried ...

1

You're hitting on some of the considerations that led Einstein to his 1905 "Elektrodynamik bewegter Körper" paper. In form of the Lorentz force law you state, the force is the electron's velocity relative to your present frame. The magnetic field $B$ is also as measured in your present frame. You are right to be worried that the whole lot might not be ...

1

The Strong Interaction is responsible for holding together the quark and anti-quark configurations that make up nucleons (aka protons and neutrons). This is due to the necesity to hold together potentially repulsive configurations of these quarks and anti-quarks. As soon as we move past a certain distance away from a nucleon (I forgot what the distance was, ...

1

The dimensions and meaning of the B coefficients are not the same as the A coefficient. The probability of spontaneous emission does not depend on the radiation environment of the atom, whereas absorption and stimulated emission do. Given that, one has a choice of how one encodes that in terms of the B coefficients, which are only a property of the atom ...

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This is almost a duplicate then of Pauli exclusion principle in an electron beam. Almost because it asks about cathode ray beams. The answer there is yes; the Pauli exclusion principle plays a role similar to the neutron star role. For an accelerator beam, where the electrons and positrons are considered free particles, as were the LEP e+ e- beams, the ...

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