Leyden Jar

This Leyden jar model has aluminum cups for its inner and outer conductors that can be separated from the dielectric (a plastic cup) to demonstrate its construction and some interesting properties. The inner cup has an aluminum charge-carrying rod and electrode ball mounted on it. When charged, energy is stored in the polariza­tion of the dielectric jar. Taking the jar apart leads to an apparent “disappearance” of the charge, since none of the compo­nents seem to have it. Putting the capacitor back together causes the charge to “reap­pear”, as the energy is still stored in the dielectric jar. Turn a van de Graff genera­tor on for a few seconds. Using a large dis­charger, connect the inner cup’s electrode ball to generator’s sphere charging up the Leyden jar. With a discharger are fully remove the inner cup. Then remove the plastic cup from inside the pouter metallic up – one can touch these cups without being shocked. One can touch any of them, in any order. Now reas­semble the jar. First set the outer cup in the outer cup and, with the help of the discharger, set the inner cup in place. Discharge the jar by touching the outer cup and the electrode ball at the same time, with the discharger. A spark will jump between the discharger and the electrode ball.