10B10.40 - Light Bulb Filament in Liquid Nitrogen
Screw the 25 watt bulb into the socket and connect to the Variac. Turn on the Variac to show that the bulb lights. Turn off the Variac and using the slip joint pliers, break the glass envelope off the bulb leaving the filament exposed. Fill the 1000 ml beaker with liquid nitrogen. Dip the filament into the liquid nitrogen so that it is completely immersed and turn on the Variac. The filament will glow and continue to do so until you take the filament out of the liquid nitrogen at which time it will burn out due to the rapid oxidation that take place in the oxygen laden atmosphere.
Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist. The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose. The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources. Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks. These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage. Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.