Displaying the equipotential lines of electric fields

The experiment P3.1.3.2 measures the isoelectric lines for bodies with different charges. To do this, a voltage is applied to a pair of electrodes placed in an electrolytic tray filled with distilled water. An AC voltage is used to avoid potential shifts due to electrolysis at the electrodes. A voltmeter measures the potential difference between the 0 V electrode and a steel needle immersed in the water. To display the isoelectric lines, the points of equal potential difference are localized and drawn on graph paper. In this way, it is possible to observe and study two-dimensional sections through the electric field in a plate capacitor, a Faraday’s cup, a dipole, an image charge and a slight curve.