I have a number of YouTube videos demonstrating various phenomena with liquid nitrogen. Click on an image to watch the clip in a popup window.
Exploding a plastic drinks bottle filled with liquid nitrogen. With the bottle sealed, as the liquid nitrogen warms and turns into nitrogen gas, the pressure inside the bottle increases. The bottle stretches before it finally explodes!
A piece of superconducting material (YBCO), cooled to below its superconducting transition temperature with liquid nitrogen levitates above a magnetic track. This is an example of Meissner effect - the weak magnetic field from the nearby permanent magnets can be expelled by the superconductor. This is because current flows in the surface of the material, generating a perfect mirror repulsive magnetic field i.e. the superconductor is a diamagnet.
Freezing fruit with liquid nitrogen.
Shattering an apple frozen with liquid nitrogen to -196°C.
Shattering an orange frozen with liquid nitrogen to -196°C.
Shattering a rubber hose frozen with liquid nitrogen to -196°C.
Shattering of a lettuce frozen with liquid nitrogen to -196°C.
Pouring liquid nitrogen, showing nitrogen steam and nitrogen beads. This is an example of the Leidenfrost effect where a liquid in contact with a surface significantly hotter than the liquid's boiling point produces an insulating vapour layer which prevents the liquid from boiling rapidly. This effect can also be seen if water is poured on the rings of an electric cooker.
A bowl of hot soapy water ... add liquid nitrogen ... watch it foam!
You can dip your fingers into liquid nitrogen at -196°C! Though only briefly. The liquid nitrogen boils forming an insulating gas layer around your fingers. Plastic cup is made from polypropylene and is very resistant to the low temperature.
A plastic cup of liquid nitrogen placed on a wooden surface boils vigorously. When lifted off the boiling reduces significantly. Shows that wood (solids) conducts heat much better than air (gas).
An inflated balloon can be cooled with liquid nitrogen. A great demonstration of the ideal gas law - as the amount of gas is fixed, as the temperature drops, the volume of the balloon decreases. If you look closely in the second part of the clip you can actually see that the air inside the balloon has been turned into liquid - mostly oxygen (bpt 90K) and some nitrogen (bpt 77K)!
A plastic bell sounds flat and dull when rung. If the bell is cooled to -196°C with liquid nitrogen, it then rings sharp and clear like a metal bell at room temperature. This is because at low temperatures the long molecules (polymers) in the plastic become fixed in place and the material is more brittle. As the bell returns to room temperature, so its ring reverts back.
Thanks to my brother Laurence and friends Chris and Liam for helping with these videos.
© 2016 Dr Matthew French All rights reserved.