An incandescent light bulb operates by passing an electrical current through a heated filament, which is typically constructed from a material with high resistance, such as tungsten. This electrical resistance generates significant thermal energy, a process known as Joule heating. When the filament reaches extreme temperatures, it emits light across a visible spectrum through incandescence. The glass enclosure and various internal structures are designed to contain the superheated filament and maintain an environment that prevents oxidation, thereby sustaining the luminosity. The efficiency of this method is fundamentally limited because a substantial portion of the electrical energy is wasted as heat rather than being converted directly into visible light.