1. What is light bulb?
▶ light bulb is a device that emits light through current. It is made of glass balls containing vacuum or inert gas.
▶ It uses electricity to heat the filament and emits light.
▶ type: LED, Incandesent bulb

2. What is material of light bulb?
Needs:Resistant to high temperatures,Thermal expansion
Filament : It is made of tungsten.
Needs:Resistant to high temperatures, transparency
Bulb's surface : It is made of glass.

3. What is properties of light bulb?
Resistant to temperaure
Styrofoam
wood
glass fiber
glass
tungsten
Tungsten : Electrical resistance is large.
Glass : The penetrability of light is good. And the most important property is cheap.