Photoelectric Definition and 11 Discussions

The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physics, and solid state and quantum chemistry to draw inferences about the properties of atoms, molecules and solids. The effect has found use in electronic devices specialized for light detection and precisely timed electron emission.
The experimental results disagree with classical electromagnetism, which predicts that continuous light waves transfer energy to electrons, which would then be emitted when they accumulate enough energy. An alteration in the intensity of light would theoretically change the kinetic energy of the emitted electrons, with sufficiently dim light resulting in a delayed emission. The experimental results instead show that electrons are dislodged only when the light exceeds a certain frequency—regardless of the light's intensity or duration of exposure. Because a low-frequency beam at a high intensity could not build up the energy required to produce photoelectrons like it would have if light's energy was coming from a continuous wave, Albert Einstein proposed that a beam of light is not a wave propagating through space, but a swarm of discrete energy packets, known as photons.
Emission of conduction electrons from typical metals requires a few electron-volt (eV) light quanta, corresponding to short-wavelength visible or ultraviolet light. In extreme cases, emissions are induced with photons approaching zero energy, like in systems with negative electron affinity and the emission from excited states, or a few hundred keV photons for core electrons in elements with a high atomic number. Study of the photoelectric effect led to important steps in understanding the quantum nature of light and electrons and influenced the formation of the concept of wave–particle duality. Other phenomena where light affects the movement of electric charges include the photoconductive effect, the photovoltaic effect, and the photoelectrochemical effect.

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  1. samy4408

    I Question about X-ray power emitted by the Coolidge tube

    hello i found this equation in a course about x rays , and i couldn't find it anywhere else they said that it is the theoretical expression of the energy spectrum , and dφ/dE is variation of the power emitted by the Coolidge tube as a function of the energy of the x ray. but i didn't understand...
  2. Boltzman Oscillation

    Classical Book for research of the photoelectric effect?

    Hi, I am not sure if this is the right place to post this but i need help finding resources for the photoelectric effect? I need to write a research paper but I do not know what I could read. The paper is for an undergrad physics course so I don't need much detail, I just need to explain the...
  3. P

    Photoelectric effect, calculating work function

    Homework Statement (Given a voltage against frequency graph) Calculate the work function of Sodium and state any assumptions you have made. My question is, what assumptions have I made? Homework Equations hf = work function V = IR The Attempt at a Solution I know on a Voltage against...
  4. C

    Does charging metal negatively decrease the work function?

    Since positive charge on the photocatode increases work function of electrons, does charging metal photocatode negatively decrease work function? If not, why?
  5. CarmenGonzalez

    [Nuclear Physics] photoelectric peak

    Homework Statement The material of which a gaseous detector is constituted has the following values of mass attenuation coefficients for a given photon energy: Rayleigh: 0.0084 cm2 / g Photoelectric: 0.071 cm2 / g Compton: 0.022 cm 2 / g Calculate the relative intensity of the photoelectric...
  6. C

    Photoelectric effect : retarding potential with back current

    In the experiment of the determination of ##h## using the photoelectric effect produced by light emitted by led's there is the systematic problem of the "dark current" or "back current", i.e. the current caused by photoelectric effect on the anode of the system which is used in the expreriment...
  7. Metals

    B Photoelectric effect and atomic excitation

    A few quick questions I'd like cleared up: 1) Alkali metals are said to have a really low threshold energy, enough for visible light to cause the photoelectric effect. Does this mean if I aim a flashlight (turned on) at a piece of sodium, I could ionise it? Simply flashing a light over a piece...
  8. DavidReishi

    I Technical question about modern Double Slit w/ one photon

    My question is about the experiment in which detectors are used behind the slits to determine which slit the photon goes through. Specifically, it's about the detectors themselves. What I found is that these detectors are some kind of photoelectric detectors. My question is this. During the...
  9. J

    Are photons really particles or just a misconception?

    Hello everyone, thanks for reading I'll explain my question. At first, light was described as electromagnetic waves, until Einstein proposed the photoelectric effect and thus creating the concept of photon, a particle of light with momentum and energy, but no mass. It could explain why the...
  10. A

    List of Photon-Matter Interactions

    Hi there, I've been reading a textbook on Physics as applied to nuclear medicine, in particular focusing on how photons interact with matter. The textbook states (without reference) that "there are nine possible interactions between photons and matter, of which only four are of significance to...
  11. B

    Photoelectric current: why does it decrease?

    In my book it is stated.When you keep the intensity constant and decrease the wavelength the photoelectric current decreases but I can't understand why? I thought it would stay the same since photoelectric current depends on the intensity of photons as more number oh photons means more e- released