Demo 17-11 Lightning Rod

The purpose of a lightning rod is to avoid lightning by continuously discharging the clouds above the lightning rod before the charge can build up and cause lightning. A lightning rod, being a sharp point, creates a large local electric field in the same way as the wand of Demonstration 17-09, thus discharging the clouds at a relatively low potential. The video shows lightning created by a large Wimshurst machine discharging to a house. As the grounded lightning rod is raised from the center of the house, as seen in Figure 1, the charge is collected at a low potential, and the lightning discharge ceases