# Tagged Questions

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 would happen if Large Hadron Collider would collide electrons?

After some reading about the Large Hadron Collider and it's very impressive instruments to detect and investigate the collision results, there is a remaining question. What would happen if the ...
1answer
2k views

### Are all electrons identical?

Why should two sub-atomic (or elementary particle) - say electrons need to have identical static properties - identical mass, identical charge? Why can't they differ between each other by a very ...
3answers
1k views

### Electrons faster than speed of light

While looking at some exercises in my physics textbook, I came across the following problem which I thought was quite interesting: It is possible for the electron beam in a television picture tube ...
4answers
2k views

### Why is the charge naming convention wrong?

I recently came to know about the Conventional Current vs. Electron Flow issue. Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and ...
10answers
3k views

### Does 'electricity' have mass? Is 'electricity' tangible?

Background: I'm in a legal academic discussion about the status of electronic 'goods' and whether they qualify as 'goods' in the same way a chair and a pen do. In this context (and specifically at the ...
2answers
392 views

### What is the mass density distribution of an electron?

I am wondering if the mass density profile $\rho(\vec{r})$ has been characterized for atomic particles such as quarks and electrons. I am currently taking an intro class in quantum mechanics, and I ...
4answers
2k views

### Why do electron and proton have the same but opposite electric charge?

What is the explanation between equality of proton and electron charges (up to a sign)? This is connected to the gauge invariance and renormalization of charge is connected to the renormalization of ...
3answers
301 views

### Current in a simple circuit

I was going over my notes for an introductory course to electricity and magnetism and was intrigued by something I don't have an answer to. I remember my professor mentioning, to the best I can ...
2answers
129 views

### What happens in electron-electron collisions?

What are the results of high energy electron electron collisions? Are other particles created?
1answer
446 views

### Why are noble gases used for lights?

I know that neon is used in advert signs due to its inertness. However, I am not entirely sure how the inertness is exploited. I think it is because Ne being inert means that after electricity frees ...
4answers
3k views

### How fast do electrons travel in an atomic orbital?

I am wondering how fast electrons travel inside of atomic electron orbitals. Surely there is a range of speeds? Is there a minimum speed? I am not asking about electron movement through a conductor.
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### What was missing in Dirac's argument to come up with the modern interpretation of the positron?

When Dirac found his equation for the electron $(-i\gamma^\mu\partial_\mu+m)\psi=0$ he famously discovered that it had negative energy solutions. In order to solve the problem of the stability of the ...
3answers
432 views

### Electrons in CRT

In a CRT, where do the ejected electrons go after they cause fluorescence on the screen, have they lost most of their energy, or do they actually go through the glass?
4answers
1k views

### Spontaneous pair production?

So I've been looking into particle-antiparticle pair production from a gamma ray and don't understand one thing. Let's say I have a 1,1 MeV photon and it hits a nucleus - electron-positron pair with ...
1answer
606 views

### Why doesn't orbital electron fall into the nucleus of Rb85, but falls into the nucleus of Rb83?

Rb83 is unstable and decays to Kr-83. Mode of the decay is electron capture. Rb85 is stable. The nuclei Rb83 and Rb85 have the same charge. Rb85 is heavier than Rb85, but gravitation is too weak to ...
6answers
421 views

### How low can an electron go?

Title says it all - recently I encountered a strange homework exercise on de Broglie dual theory with an electron wavelength of few millimeters - which implies the velocity lower than 1 m/s. I ...
2answers
282 views

### Is there a published upper limit on the electron's electric quadrupole moment?

I understand an electric quadrupole moment is forbidden in the standard electron theory. In this paper considering general relativistic corrections (Kerr-Newman metric around the electron), however, ...
3answers
509 views

### Measuring the spin of a single electron

Is it possible to measure the spin of a single electron? What papers have been published on answering this question? Would the measurement require a super sensitive SQUID, Superconductive Quantum ...
2answers
143 views

### Do the energy levels of electron orbitals change relativistically?

When an electron emits a photon from changing energy levels, the frequency of the photon depends on the difference between the energy levels. But if someone is moving with respect to the atom, the ...
1answer
186 views

### drift velocity of electrons in a superconductor

is there a formula for the effective speed of electron currents inside superconductors? The formula for normal conductors is: $$V = \frac{I}{nAq}$$ I wonder if there are any changes to this ...
2answers
1k views

### How does electricity propagate in a conductor?

On a systems level, I understand that as electrons are pushed into a wire, there is a net field and a net electron velocity. And I've read that the net electron drift is slow. But electricity ...
3answers
520 views

### Electrons - What is Waving?

If an electron is a wave, what is waving? So many answers on the internet say "the probability that a particle will be at a particular location"... so... the electron is a physical manifestation of ...
4answers
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### How do electrons “know” to share their voltage between two resistors?

My physics teacher explained the difference between voltage and current using sandwiches. Each person gets a bag full of sandwiches when they pass through the battery. Current = the number of people ...
4answers
672 views

### Why photons transfer to electrons perpendicular momentum?

Linear antenna directed along z, photons (EM waves) propagate along x. Momentum of photons have only x component. Why electrons in antenna have z component of momentum?
1answer
132 views

### What happens to 5 electrons on a sphere?

Let's suppose we put 5 electrons on a perfectly conducting (no resistance at all) sphere. There's no equilibrium configuration with 5 (though there is with 2, 3, 4 or 6). So will they keep moving on ...
2answers
2k views

### How does electron move around nucleus?

I need to get a nice picture about how electron moves around nucleus? I find concept of probability and orbitals quite difficult to understand?
1answer
60 views

### Do electrons need specific energies to excite electrons

Photons need specific energy levels, equal to the difference between two energy levels to excite an electron in an atom. Is this the same case with electrons that collide with atoms?
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951 views

### What is the difference between a neutron and hydrogen?

Differences? They are both an electron and a proton, since the neutron decays to a proton and an electron, what's the difference between a neutron and proton + electron? so is it just a higher binding ...
1answer
331 views

### Can electrons move through vacuum?

I studied that electronics is the branch of physics which deals with the practical applications of moving electrons through vacuum, semi-conductors and gasses. Can electrons move through vacuum?
2answers
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### What happens where an electron is annihilated by a spontaneously generated positron-electron pair?

I was visiting the Australian Synchrotron earlier today as part of a tour group; as the guide was going over the booster and storage rings I was reminded of something I learnt of quantum. If I know ...
3answers
4k views

### What happens when we connect a metal wire between the 2 poles of a battery?

As I remembered, at the 2 poles of a battery, positive or negative electric charges are gathered. So there'll be electric field existing within the battery. This filed is neutralized by the chemical ...
3answers
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### Do electrons in multi-electron atoms really have definite angular momenta?

Since the mutual repulsion term between electrons orbiting the same nucleus does not commute with either electron's angular momentum operator (but only with their sum), I'd assume that the electrons ...
1answer
182 views

### How many states can a n qubit quantum computer store?

A classical computer composed of '0' or '1' transistors stores $2^n$ states. Is it true that a quantum computer composed of '0' or '1' or '0 & 1' qubits stores $3^n$ states?
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### How to know what materials are good conductors of electricity?

I'm not asking a question like "Is the wood conductive?". No. I'm asking what properties do they have to have to be good conductors. Theoretically I mean. Thanks.
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164 views

### Do protons exchange photons with electrons?

I'm sorry for this question but, I just don't get it. According to the electromagnetic field theory, electrons repel each other by exchanging photons. How do protons attract electrons, by photon ...
1answer
276 views

### How would Kohn-Sham orbitals differ from 'true' elecron wavefunctions?

How would the non-interacting electron orbitals from a perfect DFT solution for a given potential shape differ from the 'true' electron wavefunctions? Or can you only really talk about the total ...
1answer
150 views

### Stability of a rotating ring of multiple electrons at relativistic speeds

There was a time when physicists where concerned about electron internal structure. The rotating ring model was one of the proposals to explain how a charge density could become stable against ...
1answer
280 views

### Why can free lithium atoms not take part in an Auger process?

Shouldn't it be possible for an incoming photon to excite one of the 1s electrons to a 2p state (or one of even higher energy) and then for the excited electron to drop back to 1s and kick out the 2s ...
2answers
149 views

### Why the K shell only contains 2 electrons?

It is written in my quantum physics book that the K shell contains only 2 electrons due to the Pauli principle. I know that if $n = 1, l = 0, m = 0$, then the Hilbert space associated to the spin is ...
4answers
669 views

### Where is spin in the Schroedinger equation of an electron in the hydrogen atom?

In my current quantum mechanics, course, we have derived in full (I believe?) the wave equations for the time-independent stationary states of the hydrogen atom. We are told that the Pauli Exclusion ...
4answers
471 views

### How do electrons jump orbitals?

My question isn't how they receive the energy to jump, but why. When someone views an element's emission spectrum, we see a line spectrum which proves that they don't exist outside of their orbitals ...
3answers
1k views

### Electron Positron annihilation Feynman Diagram

I am having some trouble understanding this fenyman diagram, it seems to indicate that the electron produces the positron, as the arrow of the positron is pointing from the electron. Additionally ...
4answers
956 views

### Bohr's model of an atom doesn't seem to have overcome the drawback of Rutherford's model

We, as high school students have been taught that-because Bohr's model of an atom assigns specific orbits for electrons-that it is better than Rutherford's model. But what Rutherford failed to explain ...
2answers
363 views

### Is the free electron wavefunction stable?

The wavefunction of a free electrons is variously described as a plane wave or a wave packet. I am fairly happy with the wave packet, as it is localised. But if we change to the electron's rest ...
2answers
382 views

### How do electrons know that?

The current is maximum through those segments of a circuit that offer the least resistance. But how do electrons know beforehand that which path will resist their drift the least?
2answers
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### Regarding the free electrons on the conductor

In a metal, why don’t the free electrons fall to the bottom of the metal due to gravity? Also, charges in a conductor are supposed to reside on the surface so why don’t the free electrons all go to ...
3answers
159 views

### What if $\gamma$-rays in Electron microscope?

I was referring Electron microscopes and read that the electrons have wavelength way less than that of visible light. But, the question I can't find an answer was that, If gamma radiation has the ...
2answers
298 views

### Why do electrons around nucleus radiate light according to classical physics

As I navigate through physics stackexchange, I noticed Electron model under Maxwell's theory. Electrons radiate light when revolving around nucleus? Why is it so obvious? Note that I do not know ...
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### In electromagnetic radiation, how do electrons actually “move”?

I've always pictured EM radiation as a wave, in common drawings of radiation you would see it as a wave beam and that had clouded my understanding recently. Illustration on the simplest level: ...
2answers
142 views

### Thought experiment with entangled electrons

Suppose we start out by having two entangled electrons. We separate them by some distance and we put one electron inside a thin loop of wire connected to an extremely sensitive voltage measuring ...
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