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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Does current flow in the valence band in p-type semiconductors?

In p-type semiconductors, when the acceptor gains an electron, it creates a hole in the valence band of the semiconductor. From what I understand, the holes create the current in this case. Does it ...
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Do virtual electron-positron pairs have mass?

When a photon produces an electron-positron pair, do both these particles have mass? Why or why not?
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What rules govern the absorption of photons by electrons when the photons exceed the work function of the material?

I am currently watching a series of lectures on Nuclear Physics. One of the topics covered is the emission and absorption of X-Rays. This got me thinking about some of the physical chemistry I took as ...
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Difference between electrons from atoms of different elements?

Is there is any difference between electrons from different elements?
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Can an electron be inside the nucleus? [duplicate]

I recall hearing one, uh, "unorthodox scientist", who has his own physics theory of "ropes" pulling on atoms. The name is something like Geade? (I think he also denies any repulsive forces, he says ...
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The charge of an electron is a constant. In any case? [closed]

Since Millikan it is obvious that the charge of the electron can be measured as a result of the force exerted by an external electric field. What we get in detail is the charge from the excess of ...
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What is the attenuation rate of an electron beam in air?

I'm trying to find some documentation that indicates the attenuation in intensity of an electron beam in air at normal pressure. Is there a rule of thumb for how quickly this occurs, for a given beam ...
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Generalisation of the density states of phonons

Is it possible to generalize de density of states for phonons $\left( \left(\frac{L}{2\pi} \right )^3 \int \frac{dS_\omega}{v_g}\right)$ to a density of states which is also applicable to Bloch ...
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Electron's velocity speed and angle with time [closed]

An electron follows a helical path in a uniform magnetic field, does its velocity, speed and angle changing with time?
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An electron leaves a neutral droplet. After that, a singly-charged positive ion joins the droplet. What is the resulting charge of the droplet? [closed]

I know an electron's charge is $~1.6 × 10^{-19} C$, which would mean that after leaving it would leave the droplets charge as $+1.6 × 10^{-19} C$ (right?) but I do not understand the effect of the ion ...
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Plasma behavior around the Electric spark in air

When a pointed cathode and a plane anode are subjected high voltage dc and there is air between them, and spark is formed and the spark is allowed to sustain for few micro seconds, how the electrons ...
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Is the electron spin $g$-factor value implying the particle is a composite one?

As I understood the highest possible value for a magnetic moment of a point charge having the same amount of charge as an electron and rotating with same electron velocity and confined in the same ...
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What are the effects of accelerating a static/stationary electron in a vacuum

The questions I ask are based on the peculiarities of quantum physics that I except but don't necessarily understand. Thought experiment: If you are able to place a single static electron in a vacuum ...
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What would happen if a body possessing a charge $(-1) \text { e}$ is brought into contact with an electrically neutral object?

Let's say that a body $A$ possesses a charge of $-1 \text{ e}$ (electron) and another body $B$ is electrically neutral (has a charge of $0 \text{ e}$). Now, if we bring any two objects in contact, ...
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At what radius from nucleus does an electron reach the speed of light?

Let's forget about the quantum knowledge here. Lets say that we just want to know what speed an electron can get, when falling straight on to a nucleus. It does not miss the nucleus and start ...
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Why do photoelectrons from a vacuum photocell move towards the collector plate if it is not charged? Has it been charged beforehand?

Why do photoelectrons from a vacuum photocell move towards the collector plate if it is not charged? Has it been charged beforehand, or do they simply move forwards because of the kinetic energy they ...
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Heavy charged particle collisions with electrons of relatively large energy

I am told that, when a heavy charged particle passes through a substance, some (small number of the) collisions occur with electrons of relatively large energy. I am then told that the maximum energy ...
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Energy Transport in Circuits (Electromagnetic waves and electrons)

I've been reading about how energy is actually transported in electric circuits (I first read about it here: http://amasci.com/miscon/ener1.html). The description in this article of why electrons don'...
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Amount of free electrons in a metal

How can I calculate the amount of free electrons in a metal? I search the forum but found nothing What I want to know is how many electrons can I remove from a metal using photoelectric effect (...
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How did J.J. Thompson decide that the electron was negative charge? [duplicate]

I read Ben Franklin had it wrong by stating "current is the flow of positive charge". Right from the start Ben Franklin could have easily decided to say that current is the flow of negative charge. ...
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Charge of elementary particles

For all the particles we know, except for the quarks, so like muon, proton, tau, bosons, neutrino, gluon, Higgs boson ecc. ecc. Is the charge always $q=0,\pm 1$$e$? Does a particle with fractionary ...
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Can a chain reaction of photon->electron->photon->electron be possible?

Unless I'm wrong, I know that if a photon strikes an electron at the right frequency, the electron jumps to a higher energy orbit, and then comes back to its stable energy state. While coming back, it ...
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Free electrons in materials with high resisitivity

I want to understand why exactly resistors or materials with high resistivity difficult the flow of current. If I'm not mistaken, there are not many free electrons in this materials to move and ...
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Can electrons transition within energy bands, or must they transition from one band to another?

A while back, I asked a question about the absorption of different wavelengths by matter (see this post). I received some excellent answers that prompted to undertake some more in-depth research, ...
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Why do electrons in a conductor not connected to a power source not fly away due to repulsion?

Let's assume that a conducting element is kept on a table (to indicate that no power source is connected across its ends). So, all the electrons move in random directions and repel each other. The ...
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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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Orbital angular momentum of a electron

I am a high school student. My query is that I have read somewhere that orbital angular momentum is related to the motion of the electron or any subatomic particle (I know that this is not the same as ...
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Do the hydrogen atom's electron orbitals have Gaussian probability density functions?

In this article they show the following diagram: Are all the diagrams in the little boxes really just Gaussian probability density functions with mean and variance (or covariance)? If not, what kind ...
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Radiation of an electron around a nucleus

As far as I know, a electromagnetic field can be generated by a variable magnetic field. The other thing I know is that, before the Bohr Hydrogen atom, the problem related to electrons around nuclei ...
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How were the oil drops in the millikan oil drop experiment negatively charged?

In this picture(all others on google are the same), the positive plate is at the top and the negative plate is on the bottom. This means for this experiment to make any sense, the oil drops must be ...
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Kallen-Lehman and one particle state of electron for QED

We did the Kallen-Lehman procedure in lectures for phi to the fourth theory. We also defined the wavefunction renormalisation. At the end our lecturer briefly mentioned that to carry it over to QED ...
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Selections rules for spin

what do we mean by the selection rule $\Delta S=0$? Can you give me some example for hydrogen atom? For example if I want to go from $1s$ to $2p$ how can I calculate $S$ for $1s$ or for $2p$?
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From where does an electron gets its energy? [closed]

From where does an electron get its energy to revolve around the nucleus? If it continues its movement, then from where does it get the energy?
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If a neutron decays to proton + electron, and a proton can decay into neutron + positron, doesn't this mean neutron = neutron + electron + positron?

I was just watching some videos and came across beta+ radiation (when a positron is emitted). It then occurred to me, how can the following be true, given that a positron and an electron have the same ...
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How does electric field propogate in a wire? [duplicate]

When I say electric field, I'm referring to the electric field that causes the movement of charge in the wire. I have learnt about currents and resistances, but I have never really had an ...
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Photons absorbed by electrons, selections rule

I know that if a photon with a certain energy $E_1$ is absorbed by an electron, for example we are talking about Hydrogen atom, if this energy $E_1$ is equal to the difference in energy between two ...
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1answer
45 views

${}$What is an electron? [duplicate]

I have been taught that an electron has a wave-particle duality nature and an electron behaves as a wave when traveling. I do also know that a wave is some kind of vibration, either it be a vibration ...
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Discharge tube phenomena

Why does Faraday dark space happen in discharge tube? Must we use flourescent to see cathode ray (electron) in vacuum tube? Why in some pressure there will be an anode ray ? I know in vacuum and ...
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Is the interaction of the electron w/ a photon in the double-slit experiment simply distorts the experience & not the consciousness of the observer?

We know that in the Young double-slit experiment, the quantum interpretation of the experiment is based on the fact that an individual particle finds itself in a superimposed state following the ...
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Kinetic theory of gases

In the kinetic theory of gases I know that the temperature of an ideal monatomic gas is proportional to the average kinetic energy of its atoms. If I give energy to the system through irradiation, ...
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Why did the specific charge of an electron show that the electron is smaller than an atom?

Why is the JJ Thomson experiment for specific charge seen as such strong evidence for the electron being smaller than the hydrogen ion? He showed that the specific charge of an electron was over 1000x ...
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Does gravity induce current?

Suppose I have a long metal copper wire (for example $100\ \mathrm{m}$ or $1\ \mathrm{km}$) and put it vertically on the earth's surface, then I put direct current (DC) of 1 ampere into it. I make it ...
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Why is the parallel component of the electron momentum preserved when passing through the solid-vacuum interface? Why is the perpendicular not?

I am reading Surface Science: An Introduction and in the chapter about angle resolved photoemission spectroscopy (page 106) it says To consider the wave vector of an electron inside the solid $k^{...
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Where does rest energy fit into the calculation of total energy?

Electron energy is often expressed as the sum of potential energy and kinetic energy : $$E = U + KE$$ In this case, where does the rest energy $511\ \text{keV}$ fit in? How can I reconcile these ...
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Does thermionic emission require vacuum?

Every source I looked at talks about thermionic emission within the context of vacuum tubes. However I was wondering if vacuum is a requirement for this effect to work. Can any cathode, if ...
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1answer
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Is electron energy spectrum quantized in the presence of an electric field?

Maybe this is a stupid question, but is free electron's energy spectrum continuous in the presence of an external field? For example, if a free electron flies between two plates in a capacitor.
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How can an object absorb so many wavelengths, if their energies must match an energy level transition of an electron?

I believe I have a misunderstanding of some principles, but I have not, even through quite a bit of research, been able to understand this problem. My current understanding of transmission, ...
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What if I insert more charge into a charged capacitor?

Suppose we have a charged capacitor with charge = $Q_1$ and then an electron beam inside the positive plate of the capacitor. The electrons entering the positive plate are repelled by the negative ...
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Movement of electrons due to current and electric field

In the channel, electrons move from the source to the right as a current. However, once electrons reach the point where the potential is $V_{DS}(sat)$, it is "swept away by the E-field" to the drain (...
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How do electron wavelengths relate to orbitals and probability density?

I'm doing a physics research project and I am a bit confused. We haven't learnt much of this on our course so I'm sorry if this is a stupid question, I couldn't seem to find an explaination that I ...

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