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Homework Help: Photoelectric Equation - SI unit question

  1. Apr 4, 2015 #1
    1. The problem statement, all variables and given/known data
    I am trying to plot a graph of stopping voltage against frequency

    The given equation is eV0 = hf - w0

    So i need to change it to the form of y = mx + C in order to plot this graph

    V0 = h*f/e - w0/e

    V0 = h/e * f - w0/e -- > V0 = y , m(gradient) = h/e , x= f and -w0/e = C (y intercept)

    V0 is the stopping voltage , h is Planck constant , e is the electron constant , W0 is the threshold frequency

    Now I am confused what SI unit does h/e has and w0/e ?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Apr 4, 2015 #2
    ##E=hf##. What are the units of ##h##?
    What are the units of work function energy?
  4. Apr 4, 2015 #3
    Work function is eV but Planck constant has Js , ev/s
  5. Apr 4, 2015 #4
    But eV is equivalent to J right? Can you represent J in terms of SI units?
    EDIT: Remember that the work function energy is also given by an identical equation, ##φ=hf_0##, but we instead use the threshold frequency. Numbers play no role in determining the units for an equation.
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