What is Electron: Definition and 999 Discussions

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. M

    How close does an electron get to a proton to be attracted

    I couldn't fit the whole question, it should say "How close does an electron have to get to a proton to be attracted to it" And I know it can depend on the speed and direction they are traveling. Can we just pretend they are stationary for this answer please. By attracted I mean the electron...
  2. Zahid Iftikhar

    I Ejection of Only one electron by a Photon in the Photoelectric effect

    Hi I am surprised to know why only one photon in photoelectric effect ejects one electron only. What if a high energy photon (not necessarily x-ray or gamma ray, which may cause Compton effect or pair production)hits the metal, say it has energy double or triple of that of the work function? Why...
  3. YMMMA

    Calculate the wavelength when electron transits.

    Homework Statement A photon of wavelength 300nm is emitted from an atom when an electron makes a transition from an energy state of -4 eV to a state of -8 eV. IF the initial state had been at enerygy of -6 eV, the wavelength of the photon emitted in a transition to -8eV is..?? Homework...
  4. T

    JJ Thomson Discovery of the Electron

    pg. 243 Falconer, I. (1987) Corpuscles, Electrons and Cathode Rays: J.J. Thomson and the Discovery of the Electron. The British Journal for the History of Science (BJHS, 1987,20,241-276). "One of their most important properties is that they are deflected by a magnetic field. This provided strong...
  5. I

    I Do electrons radiate when in free fall?

    So, I've been reading a whole bunch of different answers to this online. Some people say yes, some people say no. I'm totally confused...
  6. A

    An electron & a proton are each placed in an electric field

    Homework Statement An electron and a proton are each placed at rest in an electric field of 687 N/C. What is the velocity of the electron 56.5 ns after being released? Consider the direction parallel to the field to be positive. The fundamental charge is 1.602×10−19 C, the mass of a proton is...
  7. S

    Transmission electron microscopy -- signal type and importance

    What are the different signals we obtain from TEM and How can we distinguish between them? what are the significances of those signals?
  8. S

    B Energy of an electron = energy of photon emitted(?)

    Is it reasonable to assume that the energy of the electrons used to power a diode, equals the energy of the photons emitted from the diode? If so, why?
  9. S

    B What really is the charge of the electron?

    In my study of Quantum physics i have arrived at the natural shielding caused by photon to electron/anti-electron pair fluctuations.The shielding reduces as you get closer the electron which naturally leads me to the question.What actually is the charge on an electron?
  10. cookiemnstr510510

    Electron brought to rest by the E-field, potential difference question

    Homework Statement An Electron with an initial speed of 500,000m/s is brought to rest by an electric field a)did the electron move into a region of higher or lower potential? I b) what was the potential difference that stopped the electron? Homework Equations ΔV=ΔU/q ΔU=-W The Attempt at a...
  11. T

    I Photoelectric absorption and low energy electron absorption

    I have am currently reading Radiation Detection and Measurement, by Gleen F.Knoll, and in chapter 10 page 309. And have come across something that is causing a bit of confusion, for context the chapter is on gamma ray spectroscopy. So in the text it say's 'Thus the effect of photoelectric...
  12. I

    I Does an Electron's Field Expand at c Upon Spontaneous Creation?

    If an electron were to be spontaneously created at a point somewhere in space, would the electron's field expand outwardly at the speed of light, regardless of frame, just like how a flash of light would expand outward at the speed of light, regardless of frame?
  13. yungquark

    Unreasonable answer for acceleration of an electron in field

    Homework Statement Hello PF! Got a two-part question involving calculating the electric force on a electron when placed in an electric field of 0.75N/C to the right, and the acceleration of said electron. Our values are E=0.75N/C, q=-1.6e^-19, m=9.1e^-31 (charge and mass of electron)...
  14. E

    A Electron spin resonance in metals

    In practice, ESR/EPR seems to concern only unpaired electrons in the outer layers of organic radicals or complexes. But what about the free electrons of metals? Does it also give rise to a signal? I can't find any information on the web. Thanks
  15. A

    How was electron energy measured?

    Do you know when the energy content of electrons was actually measured as .511 MeV? was the first measurement true to current value? and, most of all, how was/is it measured with precision?
  16. D

    Minimum energy of an electron with the Larmor formula

    Homework Statement Is there a minimum value for the total energy of the electron (in this analysis)? The previous parts: Use Larmor formula to find ##\frac{|\Delta E|}{K}##, where ##|\Delta E|## is the energy lost per revolution. the result is ##\frac{8\pi v^3}{3c^3}##. ##\frac{v(r)}{c}## was...
  17. D

    Electron sprials from r_i to r_f

    Homework Statement Find an expression for the time it takes for an electron to spiral in from an initial radius ##r_i## to a final radius ##r_f##. Write your answer in terms of ##r_i##, ##r_f##, ##m_e##, e, and c. Homework Equations Larmor Formula: $$\frac{dE}{dt} =...
  18. B

    Random electron striking a neutral conductor

    if a random electron strikes a neutral conductor does it get absorbed and increase the voltage of the conductor
  19. R

    How to calculate BJT electron flow

    Hello How should i calculate number of electrons passing through it when we apply some gate voltage across it
  20. A

    Finding where an electron would be in equilibrium

    Homework Statement A point charge of -1.0 µC is located at the origin. A second point charge of 16 µC is at x = 1 m, y = 0.5 m. Find the x and y coordinates of the position at which an electron would be in equilibrium. Homework Equations F=k((q1q2)/r^2) The Attempt at a Solution I have gotten...
  21. U

    Electric potential of an electron in a capacitor

    Why is the electric potential of an electron in a capacitor measured from the negative plate and not the positive plate here? This is from Liboff Introductory quantum mechanics 1st(current is 4th) edition: I don't understand why the distance z is measured from the bottom plate if the...
  22. S

    I Massless Electron Compton Scattering: Energy of Outgoing Photon

    Hello! I found this problem where we are asked what happens to the energy of the outgoing photon in a Compton interaction, if the mass of the electron goes to zero and what is the physical intuition of it. So the formula is this: $$\lambda - \lambda_0 = \frac{h}{m_0 c}(1-cos \theta)$$ So when...
  23. QuarkDecay

    When is the Boltzmann equation applicable in a Fermi plasma?

    When do we use the Boltzmann equation for density in a Fermi plasma? n in [cm-3] and when do we use the ρ=m/V, ρ in [Kg/m3 ] (this is not an example, I just added the equations to make my question more understandable) Is the ideal gas only when we have electron and ions? Is the Boltzmann...
  24. QuarkDecay

    Electron Plasma to Muon/Proton

    Homework Statement Cylinder electron gas with density of ne= 1010 and radius or r=1cm is inside magnetic field of B=104 Gauss. If we change the electron gas with (i) muon gas (ii) proton gas does the Drift Velocity change? Homework Equations [/B] Boltzmann equation of density...
  25. J

    Electric and Magnetic field acting on an electron

    Homework Statement In the figure, an electron of mass m, charge − e, and low (negligible) speed enters the region between two plates of potential difference V and plate separation d, initially headed directly toward the top plate. A uniform magnetic field of magnitude B is normal to the plane...
  26. Deepblu

    I Why are all particles of the same type identical?

    Why all particles of same type identical? All electrons are identical to each other, all protons are identical..etc. It is as if they are copy pasted from each other! For me this is one of the biggest mysteries ever, why we don't detect more massive or less massive electrons? Is it related...
  27. I

    How is the motion of an electron around nucleus?

    How electron revolves around orbitals? Is the velocity uniform or accelerated?
  28. M

    I Dimensions of the double slits in comparison to the electron?

    what are the dimensions of the double slits in comparison to the electron? what keeps the electron from decaying outside the environment of an atom long enough to run the experiment? how are the electrons detected before and after the slits?
  29. S

    Question on electron existence comparing with others

    No physicist has ever seen an electron. Yet, all physicists believe in the existence of electrons. An intelligent but superstitious man advances this analogy to argue that 'ghosts' exist even though no one has seen one. How will you refute his argument?
  30. C

    B In night vision equipment, how does 'information' transfer?

    So I read a couple of explanations of how night-vision equipment works. Unfortunately I don't remember the sources but my recollection/understanding is that infrared light is converted into electrons and then into visible light. So my question is how does the information by which I mean (the...
  31. Nemika

    Behaviour of an accelerating beam of electron.

    If a beam of electrons starts to accelerate from rest due to a uniform electric field in vacuum will the electrons feel any mutual repulsion or attraction? Will the beam first expand then contract? If yes, how does this happen? This was a question under magnetism head.
  32. Ferdinand

    Better than electron microscopy?

    I came across your site while looking for information on how to advance our ability to view beyond the capabilities of current electron microscopy technology. I do not know where to start asking but I hoped you could point me in the right direction. I’m about to enroll in university classes and...
  33. A

    Proton vs electron, find the magnetic field for the electron

    Homework Statement A proton is projected perpendicularly into a magnetic field that has a magnitude of 0.30 T. The field is then adjusted so that an electron will follow a circular path of the same radius when it is projected perpendicularly into the field with the same velocity that the proton...
  34. fluidistic

    I How come electrons and phonons lead to the heat equation?

    Phonons on their own lead to the common heat equation. One sees that for example in insulators or non doped semiconductors. However in metals (or conductors), the electrons are the ones that are mostly responsible for the heat transfer, which extremely surprisingly to me, is also of the form of...
  35. Y

    I Effective electron mass of tungsten

    Hello! Please tell me what Effective electron mass of tungsten and Effective hole mass of tungsten?
  36. Zahid Iftikhar

    Collimation of an Electron Beam by the Anode of a CRT

    Please help me in understanding the function of anode. As in image attached you see, once the electron beam is emitted from cathode and filtered by grid, it enters into the one or series of anodes. As anode is positively charged, so, to my understanding it has no electric field inside its hollow...
  37. M

    Understanding an electron's emission of electromagnetic waves

    Hi to everybody ! I was thinking about something which confuses me about wave emission. The question is simply the following: Does an electron emit light when it accelerate? or just during its deceleration? or maybe when acceleration and deceleration alternates in some order? I'm not really...
  38. HastiM

    I How to increase the energy of an electron

    Hello, in class we learned about the hydrogen atom and in particular the quantum states describing the electron in hydrogen atom (we denoted them as usual by 1s, 2s, 2p etc.). Whenever we talked about state transitions of the electron, like transition from 1s to 2p state, we imagined an...
  39. platosuniverse

    B Does the size of the Universe change with motion?

    This is a question I was looking at based on Relativity and John Wheeler's one-electron universe theory. https://en.wikipedia.org/wiki/One-electron_universe My question is this. The faster you move towards the speed of light, wouldn't everything in the universe contract to a single particle...
  40. I

    Can one electron emit 3 colors at once?

    When light is shown through hydrogen gas, three colors of light appear. The issue I have with this is that hydrogen has one electron, meaning somehow the electron has to be emitting all three of these colors simultaneously. This, however, would be impossible since a single electron can only make...
  41. prakhargupta3301

    Between O- and F- which has higher electron affinity?

    O-- 2s2 2p5 F-- 2s2 2p6 (Fully filled hence more stable.) Since F- is fully filled as compared to O- wouldn't it require more positive electron gain enthalpy to gain one more electron than O-? However, the correct answer is given (A) Please tell me how. Thank you for reading.
  42. S

    B Understanding Energy and Charge: Exploring the Basics

    I have a simple two-part question, or two simple questions. 1. What is energy? 2. What is charge? The charge I'm referring to is the charge on charged subatomic particles. And atom's charge is defined by the number of electrons and protons present in it. But an electron itself is called a...
  43. K

    I Compton Scattering w/Moving Electron: Turner's Eq 5.29

    I beg your pardon for not writing out the math explicitly in the following. I started to do so, and realized that it would take me hours to debug my attemps at Latex! And I hope that the my explanation is clear enough that it's not needed. I've been working through R.E. Turner's "Relativity...
  44. C

    Compare the wavelengths of a photon and an electron

    Homework Statement Compare and contrast a 2.2 eV photon with a 2.2 eV electron in terms of wavelength (m).[/B] Homework Equations p = h/λ λ = h/mv The Attempt at a Solution For photon: p = h/λ λ = h/p λ = (6.63 x10-34) / (1.17 x10-27kgm/s)** λ = 5.67 x10-7 m **I have already...
  45. A

    Electron speed and acceleration in an electric field

    Hi everyone, I often work on a SEM, a type of microscope which is based on electron acceleration between an electron source and the sample you are working on. For this reason and since a few weeks I was wondering how an electron (in term of speed) behaves in a constant and linear electric field...
  46. Gene Naden

    I Paradox: Electron Radiates in a Gravitational Field

    This paradox may have come from Feynman's Lectures on Physics, or I may have dreamed it up myself. I am not sure. It has been around for a while and if you have already seen it, I apologize. I am not aware of any resolution. An electron is at rest in a gravitational field. We know from...
  47. E

    A generic quantum state and the charge of an electron

    I'm watching a lecture and the professor is talking about generic quantum states as |\psi> He's making the point that this state is very generic. It can represent anything. He references some examples like the polarization of a photon and the path of a photon and the spin of an electron...
  48. A

    I Quantum Field Theory -- Does electron have infinity size?

    Art Hobson said that quanta propagate in space to infinity. (sorry can not give a link)
  49. O

    I What an electron in an atom will do when given more energy

    Hello all, I have a question. Consider an electron in a shell of an atom has energy as 1.0ev and in the next shell it energy should be 2.7eV and the further next level energy is let's say 3.1eV. Means an energy gap of 1.7eV is their between first and second level and an energy gap o 2.1 eV is...
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