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Photoelectric effect

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  • what is photoelectric effect ?
    When light of suitable frequency falls on a metal surface, electrons are emitted from them. This effect is known as the photoelectric effect.
  • Explain why the kinetic energy of the photoelectron in the equation is equal to the maximum kinetic energy.
    Because the work function is the minimum energy required. Some electrons will need more than this minimum amount to escape the metal.
  • Why do people use electron volts as a unit of energy for problems of photoelectric emission??
    We use electron volts because if we use Joules, the quantities will be very small.
  • What is the equation of the energy of one photon ?
    E=hf, h-plancks constant, f-frequency of light
  • Explain why the kinetic energy of the ejected electron is always LESS than the energy of the incident photon.
    Because the electron uses some energy to remove itself from the metal. KE=hf-Ф
  • What is the definition of the stopping potential?
    It is the minimum potential difference required to stop the electron. (To remove all of its Kinetic energy)
  • What is the definition of the work function?
    The work function is the minimum amount of energy required to remove an electron from a metal.
  • What is the definition of threshold frequency?
    the lowest frequency of electromagnetic radiation that will result in the emission of electrons from a specified metal surface.
  • A photon of 16eV is incident on a metal which has a work function of 7eV. What is the maximum possible value of kinetic energy of electron?
    maximum possible value of kinetic energy of electron is 9eV
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