Soap Films
Material Required: Blue detergent powder, Glycerin, Bucket, Water/ Distilled water, Mild steel wire.
Soap films provide fascinating material for mathematical study. It is possible to obtain very interesting and perfectly shaped three dimensional figures using soap solutions which otherwise are difficult to create or to imagine.
To make the soap solution, pour two handfuls of blue detergent powder into half a bucket of water. If the water is hard in your area, then you need to use distilled water. Add about 25-30 ml of glycerin which strengthens the soap films obtained.
Now make wire frames using mild steel wire in different shapes. If two circular loops held one above the other are dipped in the soap solution a film stretches across both of them. By pulling the loops apart, we obtain a three dimensional shape called a catenoid. A cubical frame dipped in soap solution and pulled out carefully reveals a beautiful pattern of surfaces. There is a small cube of soap film present in the centre which is connected to the edges by planes. The figure is a projection of a 4-dimensional hypercube in three dimensions. A frame which is shaped like tetrahedron dipped in the solution similarly shows a small tetrahedron of soap film in the centre. However the tetrahedron in the centre has beautiful curved surfaces and edges. When bubble is placed between two parallel transparent plates (made of acrylic or glass), the bubble transforms into a perfect cylinder. It is quite interesting to examine what happens when more bubbles are placed between the plates.
