Magnetic field splits Cd interferometer lines on TV camera.

A magnetic field applied to a cadmium tube splits the spectral lines. Electron transitions between different energy levels in atoms or molecules produce light. When a cadmium lamp is turned on, a characteristic set of spectral lines is produced. If a magnetic field is applied to the lamp, the energy levels are split, and electron transitions between split energy levels cause a splitting of spectral lines. In this demonstration, the green spectral line is observed splitting in the presence of a magnetic field of up to 10,000 gauss. Looking through a Fabry-Perot interferometer, one sees a single set of green concentric rings that splits into twice as many rings when the magnetic field is gradually applied. In this set-up, the lens is used only to increase the visible brightness of the rings. The green filter selects only the green line from the cadmium spectra. The Polaroid (polarization vector set to vertical) eliminates the _ spectral lines which do not split, and leaves the _ spectral lines which do split. The FP interferometer is used because an ordinary spectrometer does not have enough resolution to show the lines splitting. The TV camera (JVC) must be set to focus at _ to clearly show the rings. Notes: To align the FP interferometer, look through the FP (eyes focused at _) at a sodium lamp. Adjust the rings so that they are circular and centered in the device. The center of all the optical components should be at the same height as the center of the tips of the pole pieces of the electromagnet. For more physics information, review our copy of the Zeeman video by Dr. Sumner Davis. Ref.: Experiments in Modern Physics, A.C. Melissinos, 1966, p. 309-339