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Light falls on a photoelectric surface that has a work function of 2.90 eV. If the voltage required to stop the ejected electrons is 0.210 V, what is the wavelength of the incident radiation?

  • physics -

    The energy provided by a photon is
    e*(Work function) + e*(stopping voltage)
    = (1.602*10^-19 C)*(3.11 J/C)
    = 4.98*10^-19 joules

    Set that equal to h*c/(wavelength) and solve for wavelength.

    Wavelength = 6.62*10^-34*3.00*10^8/4.98*10^-19
    = 3.99*10^-7 m = 399 nanometers (violet)

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