CHAPTER 6 Electricity In 1879, Thomas Edison created the first practical incandescent lightbulb with a carbon- ized filament. Not long after, the tungsten filament still used in today's lightbulbs was devel- oped. Since that time, incandescent electric lamps have been the standard lighting method in theatres. This chapter is intended to help you understand some of the basic principles of electricity: where it comes from and how to predict its behavior.