The experiment detects the Kerr effect in nitrobenzene, where the Kerr constant is particularly high. The liquid is in a glass vessel with a submerged parallel plate capacitor (Kerr cell). This Kerr cell is between two polarization filters: the polarizer and the analyzer. The path of the light that goes through the polarizer is parallel to the parallel plate capacitor's plates and thus perpendicular to the field lines. The light's degree and direction of polarization behind the Kerr cell can be observed with the analyzer. An electric field is established by applying a voltage to the capacitor. In this field, the nitrobenzene molecules are partial- ly polarized and orient themselves in the field direction. Light with an electrical vector in the field direction propagates more slowly than light with an electrical vector perpendicular to the field direction. In this experiment, the incident light is linearly polarized at 45° to the electric field. This light can be considered as a superposizion of two in-phase oscillating light waves, one of which is polarized in the field direction and the other polarized perpendicular to the field direction.