A photon with a wavelength of 400 nm strikes a metal surface, producing an electron with a kinetic energy of 2.5 eV. What is the work function of the metal surface?
0.5 eV
2.5 eV
3.3 eV
4.1 eV
The energy of a photon is given by
.
Therefore, the energy of a photon with a wavelength of 400 nm is given by
.
The kinetic energy of the emitted electron is given by
where W is the work function of the metal surface.
Solving for W, we get
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