You select from a variety of experiments illustrating the phenomena of modern physics.  Typical experiments are: Rydberg constant and Balmer series, Zeeman effect, charge of the electron, excitation potential of
mercury, Hall effect, absorption of photons by matter, half-life of radioactive decay, statistics of counting processes, mass of the neutron, gamma ray energies, diffraction grating, neutron activation of nuclides; X-ray diffraction, nuclear magnetic resonance, Langmuir probe.