When light of various frequencies is incident on the metal cathode of a photocell, photoelectrons are emitted from the surface of the cathode - NSC Physical Sciences - Question 10 - 2021 - Paper 1

The maximum kinetic energy of the emitted photoelectron is inversely proportional to the wavelength of the incident light. This means that as the wavelength increases, the maximum kinetic energy decreases.

The work function is the minimum energy required to remove an electron from the surface of a material. It represents the energy barrier that must be overcome for an electron to be emitted.

To find the work function (W_0), use the formula: E = W_0 + E_k(max). Using the maximum kinetic energy from part 10.1 (14.0 x 10^-19 J) and the value of E for the wavelength of light corresponding to the threshold frequency, we calculate W_0. For instance, using a wavelength of 4.0 x 10^-7 m producing E of approximately 4.06 x 10^-19 J yields: W_0 = E - E_k(max) = 4.06 x 10^-19 J - 14.0 x 10^-19 J = -9.94 x 10^-19 J.

Using the graph, find the value of E_k(max) corresponding to a wavelength of 0.5 x 10^-7 m. The maximum kinetic energy at this wavelength is approximately 16.0 x 10^-19 J.