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. C

    Momentum in a photon -> cathode collision

    Homework Statement A photon with the length of lambda hits a cathode perpendicularly to its surface. As a result, an electron leaves its surface perpendicularly to the direction of the photon. How much momentum was transferred from the photon to the cathode? The work function of the cathode is...
  2. C

    I How can an atom change from ground to excited state?

    I am currently studying a Foundation Program, which includes chemistry. -I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration. -But how can an tom changes from ground to excited state ? And can an atom changes from...
  3. danielhep

    Mastering Physics: Electron turning 90 degrees in capacitor

    Homework Statement A problem of practical interest is to make a beam of electrons turn a 90∘ corner. This can be done with the parallel-plate capacitor shown in the figure (Figure 1) . An electron with kinetic energy 2.0×10−17 J enters through a small hole in the bottom plate of the capacitor...
  4. Alan Ezra

    Accelerating an electron from speed u1 to u2

    Hi! I am trying to find the time for an electron to accelerate in a uniform electric field from u1 to u2. In the textbook, I found that time is found by integrating d(u/(1-u^2/c^2)^(1/2))=(qE/m_0)⋅dt and they get u/(1-u^2/c^2)^(1/2) = qEt/m_0 by integrating from t=0 and u=0 to t=t and u=u I...
  5. Ranku

    I Can negative pions replace electrons in atoms?

    Is Pauli Exclusion Principle alone responsible for electron degeneracy pressure?
  6. PhysKid45

    What is the Direction of the B Field from Electron Motion?

    https://scontent-ord1-1.xx.fbcdn.net/v/t34.0-12/17092376_1311006885612822_239104452_n.png?oh=72f2336f20f39bd399888901812eae3e&oe=58BAB2BF Hello PF friends. I know what the answer is, but I do not understand why the answer is. By the right hand rule I put my thumb west, but pointer up, and...
  7. gmalcolm77

    B Funneling Light to an Electron: A Size Challenge

    Assuming that the photon packet size is generally related to the wavelength of the light, say 500 nanometers and the electron approximate size of 2.82x10<-15 meters, how does the huge wavelength funnel it's packet energy to an electron approximately 1/17,730 th of it's size?
  8. Kmol6

    Parallel plate capacitor: Proton vs Electron

    Homework Statement A proton is released from rest at the positive plate of a parallel-plate capacitor. It crosses the capacitor and reaches the negative plate with a speed of 51000 m/s . What will be the final speed of an electron released from rest at the negative plate? Homework Equations...
  9. O

    A Is the electron a fundamental particle?

    According to this article an electron can be split into 3 quasiparticles: ‘holon’ carrying the electron’s charge ‘spinon’ carrying its spin ‘orbiton’ carrying its orbital location The article links to an experiment that was made in 2012, where physicists were able detect the spinion and the...
  10. J

    Electron Scattering and Bragg's law

    Homework Statement A beam of thermal neutrons (K = 0.025 eV) scatters from a crystal with interatomic spacing 0.45 nm. What is the φ angle of the first order Bragg peak? (as defined in figure 5.11, φ and the scattering angle add up to 180 degrees). Homework Equations nλ = 2dsinθ = DsinΦ d...
  11. Docdan6

    Why an electron at rest cannot emit a photon?

    Hi! Could someone explain to me why an electron at rest without any influence from a magnetic or electric field cannot emit a photon ? Could you explain it mathematically too ? Thanks in advance...
  12. G

    I Circular electron propagation in carbon nanotubes?

    Can carbon nanotubes support electron propagation perpendicular to the axis? That is, can there be circular current flow on the tube's perimeter, not just the linear flow parallel to the axis? Because I reading that it's generally considered a 1-dimensional conductor.
  13. R

    Difference between vibrational, rotational and electron temperature

    I am trying to explain the following statement in my own words... Would it be correct to say that.. I am unsure if a vibrational state is simply a different energy state or something more specific? Do the electron temperature, vibrational temperature and rotational temperature all...
  14. Jens Lundell

    B Electron in the double-slit experiment

    Newbie here: Is the (single) electron leaving the "machine" in the famous double-slit experiment the same one hitting the screen? Please give a short explanation on how this is proved, thank you.
  15. R

    Electric Fields Question, What is the speed of the electron?

    Homework Statement An electron is released from rest in a weak electric field given by -2.8 x 10^-10 N/C [PLAIN]https://www.flipitphysics.com/Content/smartPhysics/Media/Images/Tipler/Symbols/jhatbold.gif. After the electron has traveled a vertical distance of 1.9 µm, what is its speed? (Do not...
  16. Simon Peach

    B Electron moving to lower energy state

    When an electron moves to lower energy state it emits a photon, now if a photon is absorbed by an electron does the electron move back to the higher energy state. (I don't think that 'energy state' is the right term) If so how hard is it to put the photon into the electron? I assume that it not...
  17. ExplosivePete

    I The "complete state" of an electron

    I am in a quantum mechanics course based on the Griffiths text. When the books talks about the wave function on an electron in a specific state, it refers to the "complete state" of the electron as being the product of the spatial part and the spin part of the wave function. The need to...
  18. E

    B Different Frames of Reference: What's True?

    Ok I have a really basic question. Say you and I are floating in space and there is a single electron in front of us stationary to our frame of reference. Now I start hopping up and down. I see the electron accelerate up and down from my hopping frame of reference. I see a EM wave be...
  19. S

    Speed of an electron due to a ring charge

    Homework Statement A uniformly charged thin ring has radius 13.0 cm and total charge 21.5 nC . An electron is placed on the ring's axis a distance 32.5 cm from the center of the ring and is constrained to stay on the axis of the ring. The electron is then released from rest. Find the speed of...
  20. Farang

    Electron concentration as a function of pressure

    Homework Statement Determine electron concentration for both Helium and Nitrogen as a function of pressure at 300K. This is from preliminary task for Energy loss of alpha particles in gases laboratories. It's too late to submit this, I'd just like to understand. Can post more info from the lab...
  21. D

    I Physical Dimensions of electron shells

    I want to model atoms of the periodic table using OpenGL (API for 3D graphics). I was told by a physics teacher one time that this cannot be done because it's not solvable. Can you guys confirm? Apparently only the shells of the hydrogen atom has been solved meaning that I can only model the...
  22. P

    What is the energy of the electron just before it hits

    Homework Statement A 300 eV electron is aimed midway between two parallel metal plates with a potential difference of 400 V. The electron is deflected upwards and strikes the upper plate as shown. What would be the kinetic energy of the electron just before striking the metal plate? Homework...
  23. Jim Lundquist

    I Gravitational Effect on Electron Eigenstates

    As a hydrogen atom approaches a Neutron star, is the probability distribution of eigenstates of the electron in that atom influenced by the gravitational field of the star?
  24. K

    B Alpha decay produces electron surplus?

    Hi! I recently learned about the Alpha decay, where the atomic Nukleus emittes Alpha-Particles. I was wonderin if a material, which emittes such Alpha Particles has a surplus of electrons and so a negativ electronic charge after the decay. Because it loses Protons but stays with the...
  25. FallenApple

    A photon vs an electron. Wave or particle?

    So we know for a fact that an electron is a particle. The "wave" like properties are not waves at all, its just the wavefunction that is a mathematical wave which is used for getting probabilities for where the electron will end up. But what about a photon? When a charge oscillates, its gives...
  26. jlmccart03

    Find the electric field on a proton by an electron

    Homework Statement A proton is at the origin and an electron is at the point x = 0.36 nm , y = 0.34 nm. Find the x- and y-components of the electric force on the proton. Homework Equations E = kQ/r2 The Attempt at a Solution So I found that E = 9.38 * 10-28, but my problem is that I do not...
  27. lightofthemoon

    Electrostatic Potential / Work Question?

    Homework Statement An electron and a proton are held on an x axis, with the electron at x = + 1.000 m and the proton at x = - 1.000 m. If a second electron is initially at 20 m on the x axis, and given an initial velocity of 350 m/s towards the origin, it does not reach it. How close to the...
  28. FallenApple

    I MWI and path of single electron

    So in MWI, the electron takes many paths through the double slit experiment and each path is in a different world. So if electrons are fired one at a time, what makes an electron go on a certain path. Say it goes on some weird path that would have implied that a force exist when viewed...
  29. F

    I Does the electron have charge?

    I mean for the free electron Dirac equation the charge (e or q) does not appear in the equation. It only appears after its interaction with EM field. So it seams the electron does not have the intrinsic property of charge, either that or the EM is integral to the electron. Any idea?
  30. Ian Baughman

    Electron in orbit of around a single proton

    Today I was doing some reading and I came across this topic. If we have a stationary hydrogen atom with a single electron in orbit around the nucleus and want to calculate the kinetic energy of the electron we would take the following approach. 1) Using Newton's second law: F = ma ⇒ FE = mac...
  31. F

    Electric Current of an Orbiting Electron

    Homework Statement The question is based on the Bohr model with an electron with charge e and mass m orbiting a proton about a circular radius r. I have to find k in the equation I = e2 / sqrt kε0r3m where k is a some combination of constants. Homework Equations Coulumb's force law: F =...
  32. DOTDO

    Ladder operators in electron field and electron's charge

    S. Weinberg says in his book, "The Quantum Theory of Fields Volume I", that Since electrons carry a charge, we would not like to mix annihilation and creation operators, so we might try to write the field as $$\psi(x)=\sum_{k}u_k (x)e^{-i\omega_k t}a_k$$ where ##u_k (x)e^{-i\omega_k t}## are a...
  33. learis

    B Trajectory of photon or electron in double slit

    Hello, first post. I recently became interested in quantum physics and its mysteries. To my understanding, In the double slit experiment, the photon or electron will scatter and behave like a wave when both slits are open and neither slit is measured. Over time their cumulative scattering mimics...
  34. L

    An electron is fired at 4.0x10^6 m/s horizontally....

    Homework Statement An electron is fired at 4.0x10^6 m/s horizontally between the parallel plates as shown, (see attachment) starting at the negative plate. The electron deflects downwards and strikes the bottom plate. The magnitude of the electric field between the plates is 4.0 x10^2 N/C. The...
  35. FallenApple

    I Electron Degeneracy Pressure not Fundamental?

    So for what I understand, when a star collapses, the electrons do not like to overlap their quantum states because of the pauli exlusion principle. Is this different from an E&M force? If so, then why isn't it a fundamental interaction? All forces are made of a combination of the 4 fundamental...
  36. D

    Angle of electron in an electric field

    Homework Statement https://imgur.com/zEoCpc0 I am trying to figure put the angle and my attempt is tanx=sy/sx (I have calculated a value for the distances) But my book is saying: tanx =vy/vx I don't understand why my way of solving it is wrong... I don't get the same answer for x :/
  37. T

    Electron transfer and oxidation state

    When beryllium donates a pair of electrons to oxygen, that's oxidation, and the metal is Be(II). When carbon and oxygen share 6 electrons, 2 from carbon and 4 from oxygen, this is also oxidation. Of carbon. Even though it got more electrons, and even, I heard, has a negative charge. When...
  38. sliperyfrog

    An electron is launched between two plates

    Homework Statement An electron is launched between two parallel, neutral, conducting plates that are each L long and separated by a distance d with a uniform magnetic field of magnitude B permeated between them. (a) What is the minimum speed the particle must have to traverse the region...
  39. N

    I Electron Spin vs Domain Creation in Permanent Magnets

    I am having difficulty thinking through how a ferromagnetic substance is permanently magnetized. I think I understand that when for example a sample of iron is heated above it curie temperature and then exposed to an external magnetic field , the sample will become permanently magnetized. The...
  40. M

    Is <E> for an Electron in a Coulomb Field Time-Dependent?

    Homework Statement An electron in the Coulomb Field of the proton is in the state: |ψ> = (4/5)|1, 0, 0> + (3i/5)|2, 1, 1> with |n, l, m> as the quantum numbers defining the state a) What is <E> for this state? What are <L2> and <Lz>? b) What is |ψ(t)>? Which expectation values...
  41. F

    A A question about the electron self-energy correction

    In QED, 'electron self energy' to first order results from an electron emitting and reabsorbing a photon. But surely the emitted photon can be absorbed by any other electron in the universe, not just the emitting electron? Indeed it makes no sense to say the photon is absorbed by the same...
  42. F

    I Does the electron field carry information about its charge

    Does the electron field has information about its charge(strength) throughout space and if not why not? I hope this question is not vague.
  43. harini07

    General organic chemistry -- finding maximum electron density

    Homework Statement In pyrrole the electron density is maximum on which carbon atom? so if the numbering starts from nitrogen, the carbon on the right side of nitrogen let it be numbered as 2 and the next one as 3 and so on... which of the following options will have the carbons of maximum...
  44. sergiokapone

    Movement of electron in an nonuniform E and B fields

    Homework Statement The system consists of a long cylindrical anode of radius a and a coaxial cylindrical cathode with radius b (b <a). On the axis of the system has a thread with a heating current I, creates in the surrounding magnetic field. Find the smallest potential difference between the...
  45. PhysicsCheeser

    I Only One Electron? Exploring the Origin of the Claim

    I was reading through a thread and read someone say that there is really only one electron traveling through time which is why all electrons we see are the same. IS this an accurate claim? if so, where does it come from?
  46. Ags Ivana

    Semiconductor - how to find k and energy of electron, hole

    Homework Statement This is what the question looks like and I don't even have an idea where to begin since we didn't really cover this during lectures. Homework Equations This is all I have from my notes: also I found that Eg=Ec-Ev Any help appreciated Thanks
  47. G

    B Electron diffraction experiment puzzle

    In classical Physics wave theory (GCSE level) we talk about waves diffracting through a gap if the gap is similar size to (or smaller than) the wavelength of the waves. When firing fast electrons at a carbon target (teltron tube A level type apparatus) is it sufficient to say that if the de...
  48. L

    I Determining Electron Dipole: Experiments & Results

    Does anyone now what kind of experiment they used to determine that the electron is a dipole?
  49. U

    Influence of Orbitals on the mass of the electron

    If Energy levels differ in accordance to the orbital, say like 2s and 3d orbitals, then shouldn't the mass of the electron then change to uphold E=mc^2? Or is there something I am missing?
  50. P

    Electron to Stationary Proton Collision

    Homework Statement A 2 GeV electron is incident on proton (m_p * C^2 = 0.938 GeV) target at rest. Calculate the invariant mass of the electron-proton pair in the Center of Mass(CM) frame. Neglect the mass of electron which is much less than the proton mass.Homework Equations M = [P1 + P2)][/2]...
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