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Homework Help: Quantum Question

  1. Jan 16, 2015 #1
    1. The problem statement, all variables and given/known data
    Light with a wavelength 600 nm is directed at a mettalic surface with a work function of 1.6 eV. A retarding potential of 0.5 V is applied. Determine:
    a) The maximum kinetic energy, in joules, of an emitted electron before the retarding potential is applied.
    b) The maximum speed with which an electron reaches the far side after the retarding potential is applied.

    2. Relevant equations
    Kinetic Energy = hf - w

    3. The attempt at a solution
    I used the above equation to figure out "a" but, I do not know where to begin question "b."
  2. jcsd
  3. Jan 17, 2015 #2


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    Homework Helper

    Welcome to PF!

    The energy of the electron is conserved during its flight. Retarding potential means that it travels toward an electrode at negative potential with respect to the metallic surface. How much does the potential energy of the electron change?
  4. Jan 17, 2015 #3
    Oh I see but can you please do it for me I just want a solid example to follow in the future.
  5. Jan 17, 2015 #4


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    Homework Helper

    I can not do it for you, the rules of the Forums forbid it. We only can lead you.

    Do you know what is the potential energy of a charge q at a point with potential U?
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