What is Electron volts: Definition and 17 Discussions

In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacuum. When used as a unit of energy, the numerical value of 1 eV in joules (symbol J) is equivalent to the numerical value of the charge of an electron in coulombs (symbol C). Under the 2019 redefinition of the SI base units, this sets 1 eV equal to the exact value 1.602176634×10−19 J.Historically, the electronvolt was devised as a standard unit of measure through its usefulness in electrostatic particle accelerator sciences, because a particle with electric charge q has an energy E = qV after passing through the potential V; if q is quoted in integer units of the elementary charge and the potential in volts, one gets an energy in eV.
It is a common unit of energy within physics, widely used in solid state, atomic, nuclear, and particle physics. It is commonly used with the metric prefixes milli-, kilo-, mega-, giga-, tera-, peta- or exa- (meV, keV, MeV, GeV, TeV, PeV and EeV respectively). In some older documents, and in the name Bevatron, the symbol BeV is used, which stands for billion (109) electronvolts; it is equivalent to the GeV.

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  1. B

    Does Planck's relation apply to radio waves?

    I have some doubts about whether Planck's relation (E=hf) applies to radio waves. This has been bugging me because trying to apply Planck's relation to radio frequency results in some inconsistencies that I've been unable to resolve. BTW, I have no physics training, so please go easy on me...
  2. T

    I Charged particle acceleration across a potential

    Hello, I haven't been able to find the answer to this anywhere. When calculating the energy gained by a particle that is accelerated across the gap of two cavities (e.g. Dees in a cyclotron, or charged cylindrical cavities of a linear accelerator), does one need to take into account the size of...
  3. L

    Kinetic energy in electron volts

    Homework Statement How much kinetic energy is in electron volts? Homework Equations Kinetic energy = 1/2 mv2 1 electron volt = 1.6 x 10-19 J The Attempt at a Solution [/B] It's a bit unclear to me what the question is asking, since no context at all is given. It's one of the questions in...
  4. K

    Work needed to move an Electron

    Homework Statement Calculate the amount of work (in electron-volts) it would take to move an electron from 15.1 m to 16.2 m away from a +3.50 μC point charge. Homework Equations W=qΔV (?) [/B]The Attempt at a Solution None yet. I'm not even sure where to start!
  5. R

    Square Hill Barrier, weird question wording

    Homework Statement Consider a square hill barrier produced by a 10V potential. Incident upon this barrier is a steady stream of 5eV electrons. (a) If half the electrons are transmitted, how thick is the barrier? (Please derive the transmission probability rather than merely quoting it.)...
  6. B

    Understanding Electron Volts, Temperature & Boltzmann's Constant

    I need the electron volt in atomic units (mainly because I need "atomic unit" temperature). I believe that one atomic unit of temperature is eV (electron volts) / kB (Boltzmann's constant). So I know that the elementary charge e = 1 = h-bar. How do i get eV, temp, Boltmann's constant...
  7. M

    Ionization Energy in Electron Volts

    Homework Statement (10.) It requires roughly 10 eV to ionize one hydrogen atom. How much energy (in joules) are needed to ionize all the hydrogen atoms in one mole of molecular hydrogen (H2)? [Recall: 1 eV = 1.6 × 10−19 J and Avogadro’s constant is about 6 × 1023.] Homework Equations...
  8. N

    Relationship between Heat and Electron Volts in a reaction

    Hi, Im trying to understand the relationship between heat released in an energetically favourable chemical reaction and the released charged particles when the reactants are connected in a battery set up. If you mix Zinc and copper sulphate you get heat and the product. Connect the copper...
  9. majormuss

    Changing Units From Joules to Mega electron Volts

    Homework Statement I always have problems when changing units form Joule form to Megaelectron Volts and vice versa...whats the easiest way to find them? Homework Equations The Attempt at a Solution I always get confused at the conversion part.
  10. G

    Units of Electron Volts (AMeV)

    Hi, I have been viewing some publications related to space weather and have noticed that in many graphs and in the articles, the units AMeV appear very often. I am wondering what the A is for? My best guess is that means atomic, ie relating energies of ions rather than single electrons...
  11. I

    Converting Energy Lines from Electron Volts

    Homework Statement "Using the conversion factor from eV (electron volts) to Joules, determine which energy line for an electron dropping from one energy level to another in the energy diagram for hydrogen above would show a line at 435 nm in an emission spectrum." Homework Equations...
  12. V

    Why do semiconductors with wider band-gaps have higher output voltage?

    In semiconductors it is known that the wider the band-gap the higher the output voltage, what is the theory behind this?
  13. E

    Understanding Electron Volts: The Main Unit of Energy in Physics

    Help me to wrap my brain around this notion of 'Electron Volts' The lamp on the table has 120 Volts... explain this MeV...in comparison to the Lamp Bulb please. Is every type of energy measured in the form of electricity in the world of Physics? if i get this info i can move deeper...
  14. S

    Can someone explain the difference between Volts and Electron Volts?

    OK, Bear with me, I'm a mature student returning to the sciences after a 16 year break... I'm currently reading up on electricity and cannot, for the life of me, get my head around what 'appears' to be an inconsistency. Obviously my brain isn't 'seeing' the answer properly just yet so I...
  15. L

    Converting Volts to Electron Volts: Explained

    This is probably a stupid question, but how do you covert a potential difference measured in volts to electron volts? Do you just multiply the volts by e= 1.60e-19 C?
  16. 1

    What is the difference between electron volts and proton volts?

    what is the difference between electron volts and proton volts?
  17. Nim

    Half-Life vs Electron Volts: Exploring Helium Isotopes

    I was looking at a http://chemlab.pc.maricopa.edu/periodic/isotopes.html and was wondering why the half-life was sometimes replaced with electron volts? There's an example from the table below: Helium-6 806.7 milliseconds -> Lithium-6 Helium-7 160 KEV -> Helium-6...