electron

  1. F

    I How do we know the mass of an electron?

    I've been researching the proof of subatomic particles given the fact that we have never seen them before. It has always been recognized that protons, electrons, and neutrons exist; but I question how we know for certain they exist. Across my studying I've realized that in 1897, J. J. Thompson...
  2. Chan Pok Fung

    I Why is a pair of an electron and a positron unstable?

    We know that an electron and a positron will annihilate and emit gamma ray. But the electron and positron possess initial kinetic energy meaning that it is difficult for them to really collide in each other. Just like earth is not dropping into the Sun even with the gravitational pull. So I am...
  3. J

    I Electron wave funtion harmonic oscillator

    As we see in this Phet simulator, this is only the real part of the wave function, the frequency decreases with the potential, so lose energy as moves away the center. we se this real-imaginary animation in Wikipedia, wave C,D,E,F. Because with less energy, the frequency of quantum wave...
  4. T

    B Electrons cannot sense electrostatic force?

    Why there is not voltage or current just for 1ms if I connect a multimeter ground to the negative terminal of a DC power supply or charged capacitor? Why electrons in measure lead and DMM device cannot sense a bulk of electrons (or lack of it)? I tried with an 5kV DC power supply too. In an...
  5. T

    B Why can an electron go through PVC insulator

    I connected a PVC insulated alligator clip test lead to a 12V (give 20V) DC power supply positive terminal and a multimeter. After that I connected an other one to the multimeter ground, and a third one to the power supply negative terminal. I turned the multimeter to DC V measure mode. When I...
  6. M

    B Why Use Nuclear Charge In Finding Energy Value of Singular Electron?

    My Textbook says this is the formula to find energy values for electron shells: $$E_{mol of electrons} = \frac{-1312kJ}{n^2}$$ where $n$ is in electron shell number But when we divide by 1 mol to get the energy value for each electron we get $$E_{electron} = \frac{-2.178 \cdot 10^{-18}}{n^2}...
  7. P

    A Phasing 2 Electrons' Wavefunctions

    Can anyone tell me how to mathematically represent 2 phased electrons mathematically? Thank you in advance.
  8. C

    I Confusion on binding energy and ionization energy.

    1) I know that the binding energy is the energy that holds a nucleus together ( which equals to the mass defect E = mc2 ). But what does it mean when we are talking about binding energy of an electron ( eg. binding energy = -Z2R/n2 ? ). Some website saying that " binding energy = - ionization...
  9. S

    I Double Slit Experiment

    General question to members, when you look at the results and the interference pattern of the double slit experiment for electrons. Does anyone have information on what the empty space is on the screen. The electrons fixed location on the screen shows gaps always. I watched one persons theory...
  10. PORFIRIO I

    I Electrons colliding with gas molecules

    My concern is an electron tube. From what I understood so far, gas molecules will have an average velocity derived from the Maxwell distribution, and that velocity will influence in the electron collision frequency. I can't see clearly though how the electron velocity itself in the presence...
  11. Abimbola1987

    B Thermionic emission and current density

    Dear Sirs, Maybe this is general knowledge, but I couldn't find the answer where I looked, so please bear with me. Consider a circuit consisting of a mechanical generator (some spinning magnets and coils) and a wire across the generators output. At some point the wire gets hot and starts a...
  12. atommo

    B Stupid question relating to electric induction

    Hi, I've been interested in the science behind electrons/magnetism for quite a while. I've been learning quite a bit from various sources online. However there is one thing that's really nagging me. Magnetic fields result from moving electrons. That indicates that a permanent magnet has...
  13. H

    B Is the mass of the electron constant?

    If the mass of the electron has been changing during the evolution of the universe, then the orbits of the electrons would also change, which will shift the light spectrum of each atom. Could this explain red shift of far galaxies, and the shift is not because the universe is expanding? Henry
  14. B

    Carrier concentrations

    1. Homework Statement For silicon at T=300K with donor density ND=2×109cm−3, acceptor density NA=0 and ni=8.2×109cm−3, calculate the equilibrium electron and hole concentration 2. Homework Equations n_0=\frac{N_D-N_A}{2}+\sqrt{\frac{N_D-N_A}{2}^2+n_i^2} p_o=\frac{n_i^2}{n_0} 3. The Attempt...
  15. M

    B 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...
  16. T

    I 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...
  17. 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...
  18. A

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

    1. 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...
  19. yungquark

    Unreasonable answer for acceleration of an electron in field

    1. 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) 2...
  20. D

    Minimum energy of an electron with the Larmor formula

    1. 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}##...
  21. D

    Electron sprials from r_i to r_f

    1. 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. 2. Homework Equations Larmor Formula: $$\frac{dE}{dt} =...
  22. QuarkDecay

    Electron Plasma to Muon/Proton

    1. 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? 2. Homework Equations Boltzmann equation of density...
  23. 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...
  24. 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 in to visible light. So my question is how does the information by which I mean (the...
  25. 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...
  26. M

    I 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...
  27. 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...
  28. I

    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...
  29. S

    B Energy, What Is It?

    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...
  30. A

    I 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...
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