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... 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 greater ...


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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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People say the "electron" releases the energy for shorthand, but once again the energy exchanges in the photoelectric effect have to do with photon energy and the electron's orbital energies.


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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 ...


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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 ...


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The Bragg peak occurs just before the end of range because the particle deposit all of its energy near Bragg peak. Absorption $\rightarrow$ reduction in energy $\rightarrow$ more absorption. Near the Bragg peak this mechanism dominate and almost all energy is deposited in that small volume. The above energy deposition graph can not be taken as Bragg peak, ...


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Electron beams are formed in vacuum. Gas disrupts a beam. There are currents florescent lamps and carbon arc lamps. But they aren't really beams. Beams are in electron microscopes. Perhaps also sputtering systems, photomultiplier tubes, and ordinary vacuum tubes.


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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 ...


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Interesting question. Electrons have electric charge and are therefore a source of electric field. An atom can be thought as a series of energy levels in which electrons can be in. When the electron transit between these levels, the energy will be emitted as electromagnetic radiation, since the fundamental interaction involved here is the electromagnetic ...


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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 ...


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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 ...


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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 ...


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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 ...


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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, ...


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 ...


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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 ...


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The field is just assumed to be fixed over a certain region of space. Then, $v$ indicates the velocity of the charged particle moving uniform w.r.t the inertial frame of magnet. Then the force is given by $$\vec{F}=q\vec{v}\times\vec{B}$$ This is valid for a point charge. Now, suppose a person $A$ is moving on a rail cart. He has a magnet in his hand. The ...


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The reason this interests me is that no mater how fast the magnet is spinning about its axis there is no difference in the strength or direction of the magnetic field at all points in space Exactly. Your claim about the velocity of the electron being relative to the velocity of the magnet is correct. However, a spinning magnet is just that, a spinning ...


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In general, electronic relaxation of an excited atom is nothing but a quantum mechanical transition from an initial to a final state. Therefore probabilities for different transitions (what you called paths) is determined by the rules of quantum mechanics. The particular "law" that applies here is called Fermi's Golden Rule. In the related Hyperphysics page ...


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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 ...


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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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I have annotated the diagram in the Wikipedia article that you cited in your question. Note that the signs for the charges on the parallel plates were the wrong way round in the article. To simplify the derivation I assume that the condenser plate length is approximately the same as the source to aperture distance ($AS = a)$ and the angular deflections ...


0

I could be wrong, but there is a phenomenon in physics called quantum superposition. To briefly explain it, an electron can be in all possible allowed places at once until it interacts with another particle causing, in laymen's terms, the universe to "observe" it. When a circuit is closed, the free electrons are given a specific path in which they may go, ...


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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 $C_{\hslash}(q,\xi)$ ...


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, ...


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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 ...


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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 ...


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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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Yes, you can make an electron beam. And the Pauli exclusion principle doesn't prohibit it. According to the Pauli exclusion principle, two identical fermions (particles with half-integer spin) cannot occupy the same quantum state simultaneously. Here you may have missed the word simultaneously. An electron can have the same position in space (all quantum ...


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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 ...


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$$g(E)=\text{number of states at energy E available to be occupied}$$ $$f(E)=\text{probability that a state with energy E is occupied}$$ so that $$g(E) \ f(E) = \text{average number of occupied states with energy E} \\ =\text{average number of particles with energy E} = N(E)$$ So that the total number of particles will be given by $$N=\int N(E) \ d E$$ ...


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In a comment elsewhere you write that you're interested in understanding how quantum-mechanical theory describes the radiation that a hydrogen atom does and does not emit. In your question you ask about another answer that suggests some significance to the electron having zero total momentum; I think that's a feature of the coordinate system choice rather ...



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