Power supply

Power Supply
How does it get power?
Electricity flows through wires to the bulb's socket. This power source may be a battery (as in a flash light) or a distant power plant supplying your local electric utility.

what does a light bulb do?
It gives light by converting electrical energy into light energy.
Although we say the filament "burns out" it actually vaporizes over time. Some of it can be seen as darkening on the glass where it has solidified. The gas inside the glass envelope is Argon which is used because it is inert and therefore cannot unite with the filament.

Change created by Light Bulb in the World!!!

The lightbulb is probably one of the most significant inventions in science.
It has changed the world by letting people do work at night. Previously this was very hard to do because other light sources (such as candles or fires) did not provide enough light.
The full impact of the lightbulb is much larger than only reading or writing at night.
Travel: Night travel by automobiles has largely been made possible by the lightbulb. Also, light houses all over the world use very powerful light bulbs, and this provides the right guidance for all ships.
Medicine: All internal and non-intrusive medical procedures use variants of the original lightbulb.
Mining: Earlier, underground miners used torches, which also added to the carbon dioxide content in the air, and therefore made breathing difficult. With the advent of lightbulb, mining has also become healthier and safer. In carbon mines, the risk of explosion of the carbon powder contained in the air was so high that conventional fire lanterns couldn't be used (they used a tupid metal mesh covered lanterns), with lightbulbs carbon mining become safer.
Apart from this, the light bulb is used in various other fields including communications, sports, etc.