Calculate the work function in eV and calculate the stopping potential in the photoelectric effect.

Описание к видео Calculate the work function in eV and calculate the stopping potential in the photoelectric effect.

In this problem, we calculate the work function in eV and calculate the stopping potential in the photoelectric effect.

We start with a given wavelength that ejects electrons from the metal sample when the stopping potential is zero. This threshold wavelength for the photoelectric effect allows us to obtain an energy in eV for the work function or binding energy of the metal. We compute the energy of the photons by applying E=hf which we transform using c=f*lambda to apply E=hc/lambda to get the energy in eV. This is the amount of energy it takes just to remove the electrons from the metal sample. Any photons of shorter wavelength (higher energy) will also impart some kinetic energy to the electrons.

In the next part of the question, we are asked for the stopping potential using 400nm light. We calculate the kinetic energy of the electrons by using KE=hf-BE; that is, we find the energy of the photons and subtract the work function or binding energy to get the kinetic energy left in the electrons.

In this case, we obtain a kinetic energy of 0.85eV which means a stopping potential of 0.85 volts will make the current stop in the photoelectric effect experiment (this is how the KE is experimentally measured).

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