The History of the Light Bulb Feature Summary

Physics in Your World
The History of the Light Bulb
Here's what happens when a light bulb comes on and the filament is in air. Don't try this experiment at home unless you work with an adult (and even then be very careful).

The glowing filament rapidly heated the air around it, so the heated air expanded and formed the rising smoke column. But the rising gas cooled and became more dense, so it eventually stopped rising. Then the air at the top moved out to the side, forming the swirls in the photograph. To see the direction of flow within the rising air column, check out this drawing.

For an award-winning video showing how to make smoke rings and mushroom clouds, click here.
photo credit: Paal Bentdal
photo credit: Paal Bentdal
Image URL: bulb filament.jpg
June 16, 2007 - July 1, 2007