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Homework Help: Work function calculations

  1. Feb 3, 2016 #1
    1. The problem statement, all variables and given/known data
    I need to calculate the work function of a photoemissive material. Light is shone through a photocathode (cathode) and the stopping potential V, is measured between anode (stainless steel) and cathode using a picoammeter)
    Following are the data measured/calculated
    ν = 1.402 e15 Hz (deuterium lamp, at λ= 214nm)
    hν = 5.798 eV
    stopping potential, V = 2.44 v
    ϕ (anode) = 4.4 eV (stainless steel)

    2. Relevant equations
    E = hc/λ = hν
    hν = ϕ + Ek

    3. The attempt at a solution

    How do I calculate the ϕ (cathode)?
    Is the formula ϕ (cathode) = hν + V - ϕ (anode) correct?

    stopping potential V is measured in volts, everything else in the above equation is in eV. Any solutions?
  2. jcsd
  3. Feb 3, 2016 #2
    The work function (phi) has no meaning for the cathode.
    The cathode collects photoelectrons until the stopping potential is
    greater than the kinetic energy of the photoelectrons emitted from the anode.
    Also, what is the kinetic energy of the emitted photoelectrons as it
    relates to the work function of the anode?
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