A light bulb, also known as an electric bulb or incandescent lamp, is a type of lighting source that emits light and generates heat through electrical energy. Its working principle is based on the thermal effect of current: when the light bulb is connected to the rated voltage, the current passes through the filament and heats it to an incandescent state (temperature above 2000 ° C), causing the filament to heat and emit light, converting electrical energy into internal and light energy.

The biggest problem with light bulbs is the sublimation of the filament. Due to the slight difference in resistance on the tungsten wire, the temperature varies. In areas with higher resistance, the temperature rises higher and the tungsten wire sublimates faster, resulting in a cycle where the tungsten wire becomes thinner and the resistance further increases; Finally, it caused the tungsten wire to burn out. Later, it was discovered that replacing vacuum with inert gas could slow down the sublimation of tungsten wire. Today, most electric light bulbs are filled with nitrogen, argon, or krypton gas.