Electron Definition and 999 Threads

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.

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  1. D

    Lessons with electron beam deflection tube and teltron tube

    Hello, I would like to discuss with my students the deflection of electrons in electric and magnetic fields. For this purpose, I would like to perform the experiments with electron beam deflection tubes and teltron tubes. How would you implement this organizationally in the classroom? There are...
  2. D

    Diagonalizing of Hamiltonian of electron and positron system

    What I did was first noting that ##\hat{\vec{S}}_1\cdot\hat{\vec{S}}_2=\frac{1}{2}(\hat{\vec{S}}^2-\hat{\vec{S}}_1^2-\hat{\vec{S}}_2^2)##, but these operators don't commute with ##\hat{S}_{1_z}## and ##\hat{S}_{2_z}##, this non the decoupled basis ##\ket{s_1,s_2;m_1,m_2}## nor the coupled one...
  3. A

    Trajectory of an electron traveling near a current-carrying wire

    B equals 50*10^-7 T (at first instance) Fm equals 8*10^-20 N (at first instance) I know Fm is perpendicular to the velocity, and I know the estimation of the trajectory (somewhat similar to the curve y=lnx). Since I think vertical velocity will be constant, only changing the x component, I...
  4. R

    A Any electron/beta coincidence database?

    Hello All, I am aware of databases which list possible gamma-gamma coincidences for desired isotope. For example: here provides a table at the bottom with all possible gamma-gamma coincidence for Co-60. Question is, are there any similar databases/tables for electron coincidences with...
  5. Narayanan KR

    Interesting Links Between Faraday's EM Induction and EPR

    Imagine a magnet moving up and down so that its flux 'B' cuts the copper rod to produce an alternating emf, suppose if the movement is fast enough such that its frequency equals to the electron spin resonance frequency given by F = B x 2.8 Mhz per gauss, neglecting skin effect, more copper...
  6. A

    I Question about the Bohr model of atom and and electron in an orbital

    I have a question about what happen when an electron in the Bohr model of atom, gains energy because for example is "hitting" by a photon. Electron have an energy, and it is the sum of potential and kinetic. When they gain energy, they gain potential energy so they go further away from nucleus...
  7. P

    I What gives an optimum value for electron energy to ionise atom?

    There is an optimum energy which gives the greatest probability of ionisation of a particular element. This is said to align with the wavelength of the electron being close to resonances in the atom. Looking at this in a different way as particles, would it be correct to say that the optimum...
  8. M

    Electron Trajectory: Stuck on a difficult problem....

    I am very confused on how to go about with this question. The only thing I've tried so far is drawing the fbd of the electron and because of the plates the force applied would cancel which makes it centered between the two plates. As of now that is the only thing I understand, I am not sure how...
  9. Mayhem

    Particle in a box: Finding <T> of an electron given a wave function

    If ##\hat{T} = -\frac{\hbar}{2m}\frac{\mathrm{d^2} }{\mathrm{d} x^2}##, then the expectation value of the kinetic energy should be given as: $$\begin{align*} \left \langle T \right \rangle &= \int_{0}^{L} \sqrt{\frac{2}{L}} \sin{\left(\frac{\pi x}{L}\right)}...
  10. Christoffer B

    I Channel electron multiplier as an electron source

    Hi! I'm playing around with a type of electron (and by electron/molecule interactions: ion) source that was briefly touched upon in the 1960's. The basic idea is to use a channel electron multiplier "channeltron" with the anode removed; similar to a single MCP channel. The burst of electrons...
  11. A

    I Classical electron uncertainty

    In quantum mechanics it is impossible to prepare an electron in a state where both position and momentum are known with arbitrary accuracy. In classical physics such states do exist, but can they be prepared? If we assume that the electron is a classical particle (small ball of charge) can we...
  12. A

    I Electron two-slit experiment in classical electromagnetism

    Was there any study of this experiment in the context of classical electromagnetism? It is often claimed that such an experiment is impossible to explain classically, yet, the only classical model I've seen employed is Newtonian mechanics (bullets). The EM fields associated with the electrons...
  13. Narayanan KR

    A Different Way to Achieve Electron Velocity Modulation in a Klystron

    Please Notice That the Toroid Coil is Outside the Discharge Tube and yet able to influence electrons moving inside the Tube.
  14. D

    Exploring Electron Rockets for Interstellar Travel

    Hi all, Why not build an electron rocket? Why won't this idea work? Seems like someone could just hitch an electron gun onto a spaceship. Boom! Electron Rocket. I was thinking about ion thrusters. These use ions to achieve thrust. They are problematic for achieving a high delta V because...
  15. ZIKA99

    B Exploring Electron Motion in Quantum Mechanics

    I had two questions in the field of physics: We know that in quantum mechanics there is an electron in a certain distance from the distance to the nucleus as a cloud or a cover. But is motion for the cloud defined by the electron moving around the nucleus? And the main question is, can the...
  16. Ghost Quartz

    I Math of Electron Double Slit Experiment

    I'm looking for a good derivation of the "wave" patterns in this experiment. I suppose that if wave-particle duality is an obsolete idea, there must be a derivation from quantum mechanics that gets close results. Thanks in advance
  17. A

    B Electrostatic charge build up in environmental electron microscopy

    Hello, If I understand it correctly, the samples are grounded inside a scanning electron microscope (SEM) to avoid charge build up through the electron beam. Also the non-conductive are coated with a conductive layer, so they can be grounded as well. However, I do not know how the charge build...
  18. R

    B Are these actually real electrons?

    I'm curious whether the scientists actually show the real electron in this video. Thoughts?
  19. C

    I What is the quantum spin of a single electron in an (atomic) orbital?

    What is the quantum spin of the valence electron in the silver atom in the furnace in the Stern-Gerlach experiment? . Up, down, at random, alternating, in a (quantum) superposition (of both), or none? Does it even have/get one until it's measured/observed /needed? . Does the second electron, in...
  20. PainterGuy

    Lorentz transformation of electron motion

    Hi, It's not homework but I still thought I better post it here. Please have a look on the attachment. For hi-resolution copy, please use this link: https://imagizer.imageshack.com/img922/7840/CL6Ceq.jpg I think in equations labelled "12", 'e' is electric charge and Ex is the amplitude of...
  21. V

    Understanding Spherical Symmetry of Electron Clouds in External Fields

    The given diagram looks something like this: Electric force on nucleus from external field must balance attraction force from electron cloud and electric force from external field. $$e\vec{E}=\frac{k(\frac{L^3}{R^3}e)}{L^2}\hat{L}$$ where ##\vec{L}## is from center of electron cloud to...
  22. jjson775

    Electron motion after collision in a magnetic field

    Isn‘t this a straightforward problem of conservation of momentum? See attached.
  23. PragmaticYak

    Quality of an oscillating electron

    The oscillator's initial energy can be found by considering when all of its energy is potential energy. Eo = (1/2)kA2 = (1/2)mω2A2 = (1/2)me(2πν)2A2 = 2meπ2ν2A2 where me is the mass of an electron. With this in mind, the energy dissipated after one cycle is given by ΔE = E(0) - E(1/ν) = Eo -...
  24. H

    Discrepancies in Electron Wavefunction Probability Calculation?

    Hi. I would love if someone could check my solution since me and the answer sheet I found online don't agree. The probability is given by the triple integral \begin{align*} \int_0^{r_b} \int_0^{2\pi} \int_0^\pi |\psi (r)|^2 r^2 \sin{\theta} \,d\theta \,d\phi \,dr &= \frac{1}{\pi...
  25. D

    I Is there a way to calculate the frequency of an electron wave?

    According to de Broglie, the wavelength of an electron wave is L=h/p. Is there a way to calculate the frequency of such a wave? Thank you!
  26. P

    I Shooting an electron past a positive nucleus (trajectory)

    An electron is shot horizontally. There is a proton located somewhere else, but not in the horizontal path of the electron. Is there a distance of closest approach, and how do you derive it? A physical explanation would be appreciated too.
  27. H

    B Distribution of energy in the electric field surrounding an electron

    I am thinking about how an electric field has energy associated with it. If a single electron exists alone in a remote vaccuum, I believe it has it's own electric field surrounding it, and that this field has an energy content associated with it. My question is; does this electric field store...
  28. J

    B Electron charge and spin creating a magnetic field?

    From what I understand, electrons are negatively charged, however, I have recently come to learn that electrons also have a spin which creates a magnetic field around each electron. I don't understand how the electron can be a negative monopole, yet have a completely independent magnetic field...
  29. Johann0101

    Gravity's Pull: How Far is the Proton Above the Electron?

    An electron is held up against the force of gravity by attraction of a fixed proton some distance above it. How far above the electron is the proton?
  30. SimranPaudel

    Engineering How Do You Calculate the E-field in an Electron Cloud Using Gauss's Theorem?

    I tried to use the formula for electric field intensity but I feel like something is missing.
  31. D

    An electron enters a magnetic field

    Hi, I tried to solve this exercise but I'm not sure about the process. First of all, I imposed that "K = E": so that "v = √ ( (2q ∆V)/m))" then I replaced in "r = m v / (| q |B)", v with "√ ( (2q ∆V)/m))", and found out that R = (2√(2)) r. Then for the second point, I imposed Lorenz Force...
  32. D

    I Larmor precession of an electron in a magnetic field?

    In QFT where the electromagnetic field is mediated by virtual photons, is it possible to describe the larmor precession of an electron as a series of emission and absorption of virtual photons? how does the spin angular momentum "evolve" over a series of events? This feels like a challenging...
  33. T

    A Properties of Degenerate Electron Gas

    Basically the thread title. For some background, I'm trying to model laser-material interactions, where I'm assuming that the laser is interacting with a free electron gas (copper). To model the interaction, I need to determine the properties of the electron gas, such as the heat capacity...
  34. A

    I What part of physics describes what happens just outside of an electron?

    Coulomb's law for three dimensional space is an empirical law that describes the forces between two stationary point charges and is defined as: \vec{F}=\frac{K q_1 q_2 (\vec{r}_1-\vec{r}_2)}{|\vec{r}_1-\vec{r}_2|^3} From Coulomb's law, the magnitude and direction of an electric field produced by...
  35. Ale_Rodo

    Lorentz force acting upon an electron moving in a circle

    So as the summary suggests, I am studying Electromagnetism, magnetic properties of matter and Magnetization vector in particular. As a first example and to introduce the Magnetization vector (M), my textbook shows a ferromagnetic substance in a uniform magnetic field (B). Then, every atom of...
  36. D

    I Can an electron in a magnetic field radiate a virtual photon?

    In Theoretical Minimum: Quantum mechanics, Leonard Susskind describes an electron in the higher energy spin state in a magnetic field radiates a photon of energy ##\hbarγ|B_0|## and flips into the lower energy spin state. I am wondering if this photon is related to the "virutal photon" that...
  37. R

    How to find electromagnetic force between nucleus and electron?

    Hello, I'm new here and honestly I'm not a physics student. I'm studying engineering and so, understand little of physics. I am trying to find the bond force of graphene's free electron. That means, the electromagnetic force by which the electron is bound to the nucleus. I can only calculate it...
  38. Ilya B

    I Can a Black Hole be Destroyed by Electron Beam?

    Electrostatic repulsion of two electrons is about 4.17*10^42 stronger than their gravitational attraction, and is mediated by massless carriers. Black holes preserve charge, and charging a BH with even a moderate electric (negative) charge will result in BH repulsing electrons instead of...
  39. Homestar1

    B Electron angular momentum, gyroscope?

    Any spinning item, proton, electron, even planet, has angular momentum that creates force. How can an electron exist in a random orbital cloud around a spinning proton if it has an angular momentum and requires force to alter from any circular orbital plane (like a planet orbiting a star)?
  40. P

    Solving Part e of the Electron Beam Problem

    I am only asking about part e. If you are short on time, you can read through parts a - d, to get an idea of what is happening, and then attempt part e directly. I have solved parts a - d. If you would like to check your answers, the answer to part c is [rne^2 / 2e0] [ 1 - (v/c)^2], and the...
  41. M

    A What is the true energy required to excite an atomic electron?

    Energy is equal to Planck’s constant times the number of waves in 1 sec. The time scale for electronic excitation is far shorter then one second. So when we talk about the excitation of an electron from a lower level to a higher level occurring at a certain energy, are we talking about the...
  42. S

    If an electron is repelled by another electron how do we get current?

    As we know that An electric current is a flow of electric charge in a circuit and In electric circuits the charge carriers are often electrons moving through a wire. Now, since we know that Like charges repel each other then how do the electrons flow through a wire since they are like charges...
  43. J

    Compton Scattering - Find x component of electron momentum

    So I can find the initial momentum using p=h/wave = 4.98 x 10-23. Now my problem is that I don't know the final momentum of the photon nor electron, I just know the photon is scattered at an angle of 34 degrees. I know how to solve this problem if I was given the final wavelength of the light...
  44. Tareq Naushad

    I Free electron path without a nearby proton

    In absence of a positive electric field created by proton what type of behavior an electron shows? I am talking about a free electron like from a electron gun in deep space . Pauli's exclusion, orbitals, energy level etc. which are normal in an atom for electron will be absent for an electron...
  45. O

    Poynting vector and single electron in free space

    I am trying to draw the Poynting vector field for a single electron in free space between two capacitor plates. The electron is moving (and accelerating) to the positive plate at the right. I expected the Poynting vector field lines to converge to the electron, because that is where the work...
  46. I

    Chemistry Platinum ion electron configuration

    The answer is [Xe] 4f14 5d8. Why does platinum (and other 6th and 7th period d-block elements) have 4f14 instead of 4f7? Thanks.
  47. agnimusayoti

    Verify the average value of (1/r) for a 1s electron in the Hydrogen atom

    For spherical coordinate, ##dV = r^{2} \sin {\theta} dr d\theta d\phi## Therefore, $$<\frac{1}{r}> = \frac{1}{(\pi)(a_0)^{3}} \int_{0}^{\infty} {r e^{\frac{-2r}{a_0}} dr \int_0^{\pi} \sin {\theta}} d\theta \int_0^{2\pi} d\phi$$ From partial integral, I've found: $$\int_{0}^{\infty} r...
  48. lekh2003

    Momentum of Electron in a Box (IB Physics QM)

    Here's the question ^ My first thought to solving this is to use Heisenberg's uncertainty principle. $$\Delta x \Delta p = \frac{h}{4\pi}$$ Now, we approximate ##\Delta x = \frac{L}{2}##. Then, plug and chug we end up with:$$p =\frac{h}{2\pi L}$$ I thought this was it, especially because this...
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