To solve this problem it is necessary to apply the concepts related to the change of Energy in photons and the conservation of energy.
From the theory we could consider that the energy change is subject to
[tex]\Delta E = E_0 -W_f[/tex]
Where
[tex]E_0 =[/tex]Initial Energy
[tex]W_f =[/tex] Energy loses
Replacing we have that
[tex]\Delta E = 1.6-0.8[/tex]
[tex]\Delta E = 0.8eV[/tex]
Therefore the Kinetic energy of the electron once it has broken free of the metal surface is 0.8eV
