A very visual physics-related magic trick to wow your audience.
- matchboxes (one empty)
- Lie the empty matchbox flat on the table, slightly open, with the empty section facing upwards.
- Insert two matches into the empty matchbox so that the heads point out from the matchbox. Close the matchbox as much as possible so that the two matches are securely held.
- Angle the two matches so that the heads are touching.
- Rest a third match so that the head meets the other two, and the tail is resting on the table, pointing away from the empty matchbox. The three matches should now form a triangular pyramid shape with the three heads at the top point of the pyramid.
- Use a fourth match to light the others from underneath.
- Watch as the third match 'magically' rises off the table!
How Does it Work?
When the three match heads ignite they fuse together. In the case of the third match, the top and bottom surfaces of the match burn at different rates, causing a gradient in the surface temperature and tension across the match. The differing tensions across the third match cause an upward force to be exerted upon it. The two original matches are fixed in place, therefore the three match heads form a pivot point, from which the third match 'magically' rises.
Tips for Success
For the greatest amount of lift make sure that the matches are placed as symmetrically and as securely as possible.
This is a good demonstration to perform for small groups, i.e. once you have attracted a small crowd.
Did You Know?
The same effect can be seen in many domestic thermostats. It can be amplified by attaching two strips of material together with different rates of expansion (a bimetallic strip). As the temperature rises, the greater expansion on one side of the strips causes it to curve further and further. This can be incorporated into a switch that will connect and cut off a heating apparatus when a particular temperature has been reached.