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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Quantum fluctuation

According to the quantum fluctuation concept, a particle and its corresponding antiparticle appear out of nothing only to annihilate and emit some energy in the form of electromagnetic waves. Does ...
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5answers
72 views

Where do free electrons come from?

Here's what I what to know... Atoms have a nucleus that's positively charged and the negative electrons flow around it. Well when you pull the negative electrons off the atom where do the new ...
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17 views

Calculating the velocity of an electron to cause a photon to recoil [closed]

I have a question which asks me to calculate the calculate the velocity that an electron is required to have in order for a photon which strikes it to bounce back along it's incident path and for the ...
2
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2answers
74 views

Is Magnetism and Electromagnetism the Same Thing?

I keep hearing everywhere that magnetism and electromagnetism are different but is seems to me that when a current is moving and it creates a "magnetic field", it is just electrons repulsing other ...
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22 views

Motion of an electron in an Electric Field

I'm having trouble finding the acceleration of an electron which enters a constant electric field. What I know is that the velocity of the electron is $2.5 \times 10^6 \text{ m/s}$ with a mass of ...
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23 views

Is my representation of $\varphi$ Work function correct?

I am a middle-school so my understanding of physics may not be as solid as you professional physicists but never the less thought its worth a try to learn more. I read about photo-electric effect by ...
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1answer
19 views

Why the mobilities of holes and electrons are not identical in an intrinsic material?

In an intrinsic material, the lifetime $\tau$ of electrons and holes is the same, so in the equation for mobility, $$\mu = \frac{e\tau}{m^*}$$ the only difference between mobility of electrons an ...
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1answer
17 views

Do like charges separating by a small distance release a photon?

I believe from earlier physics that an electron moving from higher to a lower potential (e.g. higher energy state to a lower) can release a photon. Given two like charges -- two electrons for example ...
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3answers
54 views

What does $m^*>m_e$ imply? (the effective mass of electron is larger than its rest mass)

From what I understand, the concept of effective mass is just something people come up with to make electrons and holes obey the equation of motion $$ \vec{F}=m^* \vec{a} $$ without dealing with the ...
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3answers
57 views

What happens to the electrons when metal gets cut or broken?

For example, if I take an iron rod (or thread) and cut it in half, could it happen that one side remains with an extra electron or would it balance out too fast? If possible, do the parts simply ...
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1answer
54 views

How to calculate the speed of electrons in a metal

According to the Sommerfeld model, the electrons on the Fermi level has the relation $$ \epsilon_F=\frac{\hbar^2k_F^2}{2m_e}=\frac{1}{2}m_ev_F^2 $$ i.e. $\hbar k_F=m_ev_F$ with $k_F=(3\pi^2n)^{1/3}$ ...
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1answer
30 views

Does Red shift affect electron waves? [duplicate]

According to the De-Broglie Wave Hypothesis an electron can be considered to be a wave. Red Shift occurs due to the expansion of space(Cosmological red shift), which must expand even on the scale of ...
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492 views

How would the universe be different if the electron mass was twice as large? [closed]

Would the universe even start? Would it collapse or act differently? What if, instead, the mass changed right now? Edit: Since this is too broad lets narrow it to two scenarios: What happens to ...
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1answer
27 views

Difference in electrons excitation in Au (111) between perpendicular and diagonal orientation?

In Au (111) single crystalline as shown in attached file, is there a difference the way electrons are excited when they are excited from perpendicular and diagonal orientation as shown in the figure ...
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2answers
68 views

How is charge expressed?

I am happy with the concept of electrons interacting with each other through the emission and absorption of photons, but what I don't understand is how the negative charge on an electron is expressed ...
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3answers
30 views

Do electrons get accelerated or decelerated by the atoms of the anode during X-rays production?

The electrons striking the anode get deflected by the heavy nucleus. Though the speed may or may not change, the direction of motion changes which leads to acceleration. The charged particles emit ...
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1answer
100 views

Visualisation of electron

first things first, I'm not by any means a physicist nor a student of physics. I study graphic design. Theme of my bachelor thesis is visualisation of physical and mathematical phenomenons, long story ...
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1answer
39 views

Does positron-electron annihilation preserve enough info to reverse exactly

An electron-positron annihilation can produce a pair of gamma rays. In the reverse process, known as pair production, can the gamma rays carry enough information to determine the resulting ...
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2answers
65 views

Speed of electrons in resistors

What affects the speed of electrons in a resistor? If two resistors are connected in series, they both have the same current; same number of electrons passing at a point per second. Suppose one ...
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1answer
106 views

What is the Poynting vector of an electron?

On chapter 27 of "The Feynman Lectures on Physics Volume II: Mainly Electromagnetism and Matter", Richard Feynman says: Finally, in order to really convince you that this theory is obviously nuts, ...
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2answers
74 views

why do metals feel cold when electron moves at Fermi velocity?

This might be a very elementary question. Considering that electrons in typical metals have very high Fermi velocity, why is it that when you touch a metal you feel cold? My intuition tells me that ...
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0answers
20 views

Photon absorption by a hydrogen atom : [duplicate]

How does the photon absorption takes place in a hydrogen? The classical mechanics shows the absorption of photonic energy resulting in the excitation of atom. Intuitively, a photon with frequency ...
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1answer
30 views

Can all energetic photon excite an electron?

Consider a hydrogen atom, to excite the electron to a higher orbit, it should interact with photons of energy equal to that of the energy difference between the two states. If the energy of photon is ...
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2answers
56 views

Will Positron Cause flow of electricity?

Recently someone told me about antimatter. Antimatter is something that is completely opposite to matter. What I would like to know is let's say this universe was made of Anti-Matter. So since the ...
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1answer
26 views

What happens when an electron and an EMR meets?

The electron on an atom gets excited to a higher level when some how the energy is transferred to the electron. But I can't understand it. I'm no expert of physics. What happens when the electron in ...
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0answers
100 views

Are the left-chiral and right-chiral yukawa couplings equal?

I guess another way to ask this is: Does the "physical electron" spend EQUAL time being a left-chiral and right-chiral fermion, on average? Clarification: The electron switches between (-1/2 T3, -1Y) ...
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1answer
68 views

Does the gravity affect voltage in a circuit?

The electric current is a flow of electrons, which have mass (small, but it is still a mass). So, considering a planar circuit, do the properties of the electric current (voltage, intensity) change ...
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1answer
18 views

Help Understanding Correlations In Many Particle (Beam) Physics

I am having a lot of trouble looking at the statistical properties and having some sort of intuitive sense of correlations among different properties of many body systems (in particular charged ion ...
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1answer
35 views

Infinite Larmor precession

Say an isolated electron (meaning it's not part of an atom) is at rest and we turn on a homogeneous magnetic field around it. The electrons' spin undergoes the Larmor precession (except in the case ...
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0answers
16 views

What is Rehm-Weller equation should look like?

Rehm-Weller equation which defines the energy change for photoinduced electron transfer according to Lakowicz "Principles of Fluorescence Spectroscopy" should look like: $\Delta ...
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0answers
20 views

Couting the occupied states in band structure

I work with several dft codes and I have produced the band structures of some doped semiconductors with their plots. The problem I have is that I do not know how I can analyze the band structure and ...
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1answer
101 views

Why are permanent magnets permanent?

Let me see if I get it right. When an iron bar is attracted by a permanent magnet it becomes a magnet itself because all of its magnetic domains start to point in the same direction. When the iron bar ...
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1answer
61 views

Can we calculate L-S coupling without Dirac equation?

It is known that there exists an orbital and spin angular momentum coupling for an electron moving in the atom. And the Hamiltonian can be directly derived using Dirac equation. I want to use a ...
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30 views

Why free electron has orbital magnetic moment?

I was about to ask why don't we use electron beam instead of atoms in Stern-Gerlach experiment, then I saw this question and my question become why free electron has orbital magnetic moment...
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3answers
183 views

How is a photon measured?

If photons transmit the electromagnetic force, which is observable: the photon or the electron? Do we ever directly measure a photon, or do we only measure it's effect on electrons. For example ...
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3answers
108 views

Self-energy of electron from classical reasoning

If it takes energy to group charge together(self energy) how can it be possible for every single electrons, etc, to have exactly same amount of charge? (think of if we hold some sand in our hand, then ...
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0answers
33 views

Question on calculating the number density of free electrons in the sun's photosphere

I am writing a paper on the effect H$^-$ (a hydrogen atom with an additional electron) has on the opacity in the sun's photosphere. As such, I need to calculate its abundance. Doing so is ...
2
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1answer
27 views

How can nuclear decay both annihilate and create?

This'll be back to basics for many of you, but here's something I still don't get. How can nuclear decay of an unstable atom both create and annihilate positron-electron pairs? You have an unstable ...
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2answers
58 views

Charged particle singularity

Is it possible to manipulate magnetic/electric fields, similar to magnetic confinement technologies/penning traps, to compress charged particles into black holes?
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1answer
62 views

The “classical radius” of the electron [closed]

According to one theory, the mass m of the electron arises simply as a consequence of the electrostatic energy of its electric field, through Einstein's famous expression ε=mc^2, where ε is the field ...
8
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1answer
126 views

If protons and electrons had similar masses

If electrons and protons had the same mass, would they still be in a stable orbit around their barycenter, or would they eventually collide? Similarly, a positronium(or protonium) only lasts extremely ...
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2answers
50 views

Is it possible for electrons to carry more than one charge?

Sorry if this has been asked before. Could also be a really basic question (new to electrical study). I am a bit confused about the relationship between electrons and charges. So what I understand is ...
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0answers
35 views

Charge density within radius r from the nucleus

The probability of finding an electron within radius $r_b$ for Hydrogen near the center ($r_b<< a_0$) is approximately equal to zero (according to 1s orbital curve). Does this imply that the ...
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2answers
2k views

Why don't free electrons fall from metals if shaken?

This is a question we were asked at a physics lecture.
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4answers
93 views

Can neutrons be synthesized purely from protons and electrons?

Can neutrons be synthesized purely from protons and electrons? Note: I'm looking for reactions that do not require neutrinos or any particles besides just protons and/or electrons as reactants.
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1answer
35 views

Why in PN junctions the octet rule is dominating electrostatic repulsion?

The depletion region in PN junctions is created by charges from the N part diffusing into the P part, thus completing an octet of covalent bonds in the P part. This shift however leaves positive ions ...
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85 views

Photoelectric effect Experiment - What's the voltage bias of the set up?

What's the bias of the setup? Forward / Reverse? I'm doing a photoelectric effect experiment.The experimental setup involves a photocell, which has an emitter (cathode) Potassium and a ...
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1answer
25 views

Foucault currents with a simple pendulum

I have this diagram : It's a kind of pendulum; when it swings, it passes through a small aera where there is a magnetic field. Therefore, the electrons moves towards the bottom because of a Lorentz ...
0
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1answer
54 views

Question about one of the problems of the Bohr model

This is probably extremely basic physics that I don't know, but I'm still going to ask: Say in hydrogen, according to the Bohr model the electron is "really" orbiting the proton, and as a consequence ...
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1answer
141 views

Can an electron stand in place of proton like a ghost standing in place of you?

The atomic orbital refers to the physical region where the electron can be calculated to be present, as defined by the particular mathematical form of the orbital 1. The picture below shows the $1s$ ...