Why do light-bulb filaments go out?

08/13/16

“Why do light-bulb filaments go out?”

 

We all know what electric light bulbs are and what they do, they are some of the most omnipresent devices in human civilization. However, have you ever wondered why they die out? Well, let’s think about it like an engineer

For a quick review, light-bulbs work by pushing a current  through a tungsten filament. This filament acts as a resistor, absorbing current as heat and giving off light. However, as this filament gets used more and more, this filament will become damaged and brittle from effects such as thermal expansion and joule heating, especially during the initial starting phase (in fact, light-bulbs actually last longer if they are kept on permanently). Eventually, this filament will wear out, and the light bulb will be rendered useless. Light bulbs take up so much power, that up to 24 percent of a home’s electricity bill is used for lighting!