The electron is a subatomic particle, symbol e− or β−, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry and thermal conductivity, and they also participate in gravitational, electromagnetic and weak interactions. Since an electron has charge, it has a surrounding electric field, and if that electron is moving relative to an observer, said observer will observe it to generate a magnetic field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law. Electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields. Special telescopes can detect electron plasma in outer space. Electrons are involved in many applications such as tribology or frictional charging, electrolysis, electrochemistry, battery technologies, electronics, welding, cathode ray tubes, photoelectricity, photovoltaic solar panels, electron microscopes, radiation therapy, lasers, gaseous ionization detectors and particle accelerators.
Interactions involving electrons with other subatomic particles are of interest in fields such as chemistry and nuclear physics. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms. Ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge 'electron' in 1891, and J. J. Thomson and his team of British physicists identified it as a particle in 1897 during the cathode ray tube experiment. Electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. The antiparticle of the electron is called the positron; it is identical to the electron except that it carries electrical charge of the opposite sign. When an electron collides with a positron, both particles can be annihilated, producing gamma ray photons.
I'm asking mainly about part (c). Within the context of BBN, I'm a little unsure how you account for different baryons (i.e. does ##n_b## include neutrons, protons, hydrogen and helium, given that helium itself contains both neutrons and protons?)
For completeness, for part (b) I would just use...
According to STR: E=MC^2.
When an electron and proton are independent( without influence of any kind of fields, especially electrostatic fields )their rest masses are Me and Mp. When they combine to form Hydrogen atoms they emit photons. So, some energy loss in the form of photons. So, now...
Flash memory depends on tunneling in order to work—electrons have to tunnel through an oxide layer. Now, the wavelength of an electron is at most 24 pm. An atom is on the order of 100 nm wide, and the oxide layer must be at least several atoms thick. How can there be any significant tunneling?
Let's take the example of an electron in of a hydrogen atom . It continuously interact with the proton of the hydrogen atom . Both the proton and electron are continuous interacting with each other. It is said that wave function collapse when it is being observed or observers interact with it...
I have been doing some reading on electron reconstruction from proton-proton collisions at CERN. In some of the papers I have read, plots such as the one In the figure are included. What I would like to know is why they have chosen to plot the x and y axes as cos(phi) * tan(theta) and sin(phi) *...
Kuusela https://research.utu.fi/converis/portal/detail/Publication/32053938?lang=en_GB (published in AJP) (PDF here) describes a pseudothermal light source that can be built easily in college labs, and can be used to do some quantum correlation experiments. They propose this as an alternative...
Can we describe / explain the B x v force in the electron's own reference frame without reference to relativistic invariants, 4-vectors, tensors et al?
The aim would be to explain things like the following video without the notion of "field lines" that electrons and wires move through. But the...
Homework Statement: Real world application of freshman physics
Relevant Equations: TBD
This is not a homework question, this is relevant to my work. It seems simple enough (introductory) but I keep running into problems.
An electron is emitted from an surface (material is irrelevant, could...
Showing the motion is simple harmonic seems routine. The 5th equation on p. 674 gives ##E=frac{1}{4\pi\epsilon_0}frac{qx}{(a^2)+(x^2)}^frac{3}{2}##, but matching expressions for ##\omega=k/m## yields only ##x=frac{ea^2}{2}##. Something in the model is escaping me. Thanks for any help offered!
Quarks and electrons have clear electric polarity.
So, can we assume that an electric source as electromagnetic is needed to create those kinds of particles?
hi, while studying Majorana mass term can be added for the neutrino - as they are neutral - but cannot be added for the electron -as it would violate the charge conservation - i could not understand how charge conservation for Majorana mass term of electron is violated.
kindly help
Hello everyone,
I have the problem above. I chose to put ##F_G = F_Z## to solve it and end up with a radius ##r = 1.04\cdot 10^{-7}##m.
Solutions on the internet choose to put the gravitational force equal to the centrifugal force and obviously end up with a completely different solution. I...
The peak of the radial probability density for the 1s state is at the Bohr radius ##a_0##. But if we consider equal volumes as cartesian boxes, can one fairly say the electron has a higher probability of occupying a box near the nucleus than elsewhere because the peak of ##\psi^* \psi## is at zero?
I've known for a long time that the muon mass is approximately 3∕2×137 times that of the electron, as in Nambu's empirical mass formula from 1952. I recently wondered what the difference was as a multiple of the electron mass, using current CODATA figures for the muon to electron mass ratio and...
An electron requires an "exact" wavelength photon to transition from one level of an atom to another. Yet the wavelength of a photon has a a continuous probability distribution, implying that the point probability of achieving an exact wavelength is zero. One can only talk meaningfully about...
I've been looking at a practice test for an introductory class in quantum physics, and I've found a really weird question. It asks for an estimation of the force that an electron exerts on the walls of a box of known length during a collision.
This seems like an entirely nonsense thing to ask...
ik this is basic knowledge, that all groups go up in reactivity the further down you go in the group, except for group 7, where this is reversed.
however i don't understand why, because in group 7, the electron shielding still increases the further down the group you go, like with all the other...
I know that the Heisenberg Uncertainty principle states that the position of an electron is uncertain, however, if an electron is created due to beta decay, then at what location is it more likely to begin its movement?
Is it right inside the proton? Is it the outer edge of the proton? Is it...
Hello! I want to get the electrostatic interaction (between and electron and a nucleus), while accounting for the fact that the electron can also be inside the nucleus (e.g. in an S##_{1/2}## state). I ended up with this double integral...
I am doing the Millikan Oil Drop experiment to determine the charge of a single electron. I have been following the lab manual provided by the manufacturer, https://hepweb.ucsd.edu/2dl/pasco/Millikans%20Oil%20Drop%20Manual%20(AP-8210).pdf.
The manual defines a simple method to calculate for...
I have read, what I believe, misleading articles about generating entangled electron pairs. Some suggesting the electron is split. But this isn't possible because it's an elementary particle with charge/mass and Spin properties. So how do we achieve generating entangled electrons with opposite...
I just want to elaborate the wave nature of electron from davisson and germer experiment . there is resonance of energy (54 ev)provide to electron for which it show wave like behavior's.
give some better explanation for this.
How do you know which binding energy shell to use? In the solution it uses K and L2. Why specifically L2 and not L3 or L1 for example?
And what should I do with the information to omit electrons lower than 20kev? I initially thought that meant to omit the electron binding energies lower than...
This is SAMPLE PROBLEM 25-7 from "Physics" by Resnik, Halliday, and Krane, in the chapter "Electric Field and Coulomb's Law".
After describing the behavior of uniformly charged spherical shells:
follows a sample problem:
The solution to (a) goes to say that the volume inside R/2 is 1/8 of the...
According to Leonard Susskind, i.e. the electron has periodically interactions with the Higgs field condensate, that change the electron alternately to be right-handed an left-handed. At 44:20 in the video he says, that, according to the Dirac theory, the mass of the electron is proportional to...
TL;DR Summary: Find acceleration of electron in dB/dt >0
Hello. Here is a problem that i'm not so sure about:
Inside a solenoid there is a time-dipendent magnetic field B, so we have dB/dt = b (constant).
We want to know the acceleration of an electron:
a) placed in the center of the solenoid...
The problem of bound states of an electron trapped in a dipole field is being studied by Alhaidari and company. (See, for example, https://arxiv.org/ftp/arxiv/papers/0707/0707.3510.pdf). It is not clear to me why the point dipole approximation is used everywhere in such calculations. Can't an...
Hello! If I have a (diatomic for simplicity) molecule containing a nucleus that decays by electron capture, are there any theoretical calculations of how that would behave in practice? For example would the lifetime change? Would the resulting molecule still be bound? For example if I start with...
Specifically, this would be beta plus decay and not electron capture, and assumes an electrically neutral radionuclide. Since beta plus decay is the emission of a positron from the nucleus as a proton transmutes into a neutron, the resulting atom now has 1 less elementary charge than before, but...
How to correctly determine the temperature of electrons in an ion source based on ECR?
Is it possible to use the Saha equation?
##\frac{n_en_i}{n_a}=\frac{g_eg_i}{g_a}*3*10^{21} T^{3/2} e^{-J/T}##
Using the search, I found the McWhirter criterion for the applicability of the formula above:
##n_e...
As in title:
Plugging in the definition is straight forward, I am too lazy to type, I will just quote the book Fetter 1971:
Up to here everything is very straight forward, in particular, since we are working on free electron gas, ##E=\hbar \omega##
However, I have no idea how to arrive...
This is actually a two-part question:
1) According to the Copenhagen Interpretation, atoms have energy bands but there's no explanation of how these bands are derived, or why they only form for protons/antiprotons. Any thoughts?
2) The Copenhagen Interpretation mentions that when an atom's...
In the picture below we have two identical orbitals A and B and the system has left-right symmetry. I use the notation ##|n_{A \uparrow}, n_{A \downarrow},n_{B \uparrow},n_{B \downarrow}>## which for example ##n_{A \uparrow}## indicates the number of spin-up electrons in the orbital A. I would...
I am struggling with how to go about this; in particular, I'm not sure I understand what state is being alluded to when Ballentine says "For an electron that approaches the surface from the interior, with momentum ##\hbar k## in the positive ##x## direction, calculate the probability that it...
I did some research online and found that "When certain elementary particles move through a magnetic field, they are deflected in a manner that suggests they have the properties of little magnets." To explain this phenomenon, physicists invented the concept of spin. So far so good.
What I...
Stationary solutions to the Schrödinger equation factor into a spatial part, e.g. atomic and molecular orbitals, and a temporal part that gives the phase rotation frequency. It is often assumed that adding a constant to the potential leaves the physics unchanged. And clearly, any "spectroscopic"...
Hello,
I've seen in a few books on solid state physics that one can deduce an expression for average K.E.:
$$<\:K.E.>\:=E_c+3/2\:k_B\:T$$
from the following:
$$<\:K.E.>\:=\:\frac{\int \:\left(E-E_c\right)g\left(E\right)f\left(E\right)dE}{\int \:g\left(E\right)f\left(E\right)dE}$$
I can't...
I'm reading through Hohenberg's seminal paper titled: "Inhomogeneous Electron Gas" that help lay the foundation for what we know of as Density Functional Theory (DFT) by proving the existence of a universal functional that exactly matches the ground-state energy of a system with a given...
Since there is only one excited electron, it could come from n=3 to n =1directly or n=3 to n =2 and then n=2 to =1.
Hence, there could be one or two lines depending upon the path taken by electron.
Is this right?
When I try P_rel_e = P_ideal I couldn't get a single number that is close to the given T_Max. It might be that I used the wrong equations but I am not sure. Can anyone give me some guidence on this question?
Schrodinger’s original interpretation of the wavefunction was that it represented a smeared out charge density however this was replaced with Max Born’s probability interpretation. The issue was from what I understand that a charge density would repel and have self interactions as all the charge...
The proton and electron are described by separate wavefunctions.
When they come together in the hydrogen atom are they quantum entangled and have a joint wavefunction.
For part (a) of this problem,
The solution is,
However, why did they need to take the absolute value of the charge? I thought they could keep the original signs as shown below:
Using energy conservation, the electric force dose internal work transferring electric potential energy into...
TL;DR Summary: I have a small nut tied to a string. I take a straw and generate free electrons on it by a handkerchief. Then I thouch the nut with the straw and the nut is to be repulsed by it, because of a transfer of part of its electrons. But it does not happen, the nut is attracted to a...
I have seen many tutorials that provide steps how to transcribe a Feynman diagram into algebra, for instance [here]:
However, I have never seen the final line of the calculation converted into a real number. What are the steps to get from the algebra equations transcribed using the Feynman...
Hi,
I asked this question elsewhere, but I didn't understand the answer. It seems to be easy to understand, but for some reason I'm really confuse.
I'm not sure how to find the average position of an electron and the average separation of an electron and his proton in a hydrogen atom.
To be...