I thought I might start us off with a quick
little experiment you can do at home about surface tension.
1.
Half fill a small bowl with
water. Then sprinkle a thin layer of
ground pepper on the surface.
2.
Dip a tooth pick in the washing
up liquid. Then touch the middle of the
water with the stick’s tip.
3.
As the washing up liquid
touches the water, watch what happers to the grains of pepper. What happens to them?
4.
Half fill another small bowl
with milk. Then add two or three drops
of food dye in different places. Use lots
of different colours if you have them.
5.
Dip a cocktail stick in the
washing up liquid and touch the milk with it.
What happens to the dyes as you do this?
Washing up liquid reduces surface
tension. This allows the particles of
the water to spread out more. As they
spread out, the push the pepper specks or the food dyes so that they spread out
and merge together, creating patterns.
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