A Home Made Lava Lamp That Demonstrates Thermochemical Convection in Action and is Unlikely to Cause Fatal Injuries to Students
Abstract
It can be quite difficult to instill an intuitive sense of the scaling relationships for mantle convection to a class of geology students, but the use of various props can help. One favorite demonstration tool is the good old lava lamp which, coincidentally, first went on sale at the very time plate tectonic theory was gaining acceptance. Armed with one or more lava lamps, a lecturer can quickly impress upon students how scaling effects such as viscosity, heat input, gravitional acceleration influence the vigour of convection - a first step to understanding basic concepts such as Rayleigh number from a non-mathematical perspective. For more advanced students it is instructive to build a lava lamp for themselves because then it is necessary to understand the trade-off between chemical and thermal buoyancy, and how the equivalent scaling relationships to the purely thermal convection case play out. However, most of the recipes for lava lamps which you can find on the web involve the use of highly toxic substances, often flammable, and suggest the use of mains electricity to provide the light and heat. Needless to say, university safety officers and concerned parents are nervous about permitting such activities in student offices, dorms or at home. We share their concerns, of course, and here suggest a number of relatively safe alternatives which can be constructed from supermarket foodstuffs and cosmetic products together with heat sources such as a cappucino machine, a laptop running finite element simulations, as well as sealed chemical handwarmers.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFMED13C1149M
- Keywords:
-
- 8110 Continental tectonics: general (0905);
- 8120 Dynamics of lithosphere and mantle: general (1213);
- 8121 Dynamics: convection currents;
- and mantle plumes;
- 8130 Heat generation and transport