How to calculate the kinetic energy of photoelectron - photoelectric effect problem

 

     Solved Problem 1 -   Calculate the kinetic energy of photoelectron emitted by sodium surface when light of wavelength 400 nm is incident on it. The work function of sodium is 2.28 eV.

     Solved Problem 2 -   Calculate the value of longest wavelength which can result in emission of a photoelectron from sodium surface.

      Answer of problem 1

 Energy of incident photon

Then converting the work function from eV to Joule

                 E₁ = 2.82 x 1.602 x 10^-19 = 3.653 x 10^-19 J

                  K. E = E₂ - E₁ = 4.969 x 10^-19 - 3.653 x 10^-19 = 1.316 x 10^-19 J

      

     Answer of problem 2

      The wavelength of the incident light just sufficient to knock out the electron

See Also:

Photoelectric effect definition chemistry