Visions of Science - Einstein Year Award Announced

Robert Anderson won the Einstein Year award with this image of a paperclip held on the surface of water by surface tension. Robert took this photograph using a grille in front of the light source to create the lines reflected in the water. The lines show the distortion of the water from the weight of the paperclip which Robert related to Einstein's idea that light is bent by strong gravitational fields. See more winning images of this unique award at the Visions of Science web site.

What is surface tension?

Believe it or not water is sticky - not sticky like glue - but water molecules are very attracted to each other. If you had a glass of water, then the water molecules in the centre of the glass would be attracted to the water molecules above them, below them and to the side of them. But the water molecules on the surface of the water do not have any molecules above them to be attracted to, so they become more attracted to the molecules to the side and below them - this causes surface tension.

Surface tension can be very useful, it supports things like pond skaters and, as you can see in Robert Anderson's image, paperclips - but sometimes, like when you are doing your washing up, you need there to be less surface tension so that the grease from your dirty dishes is held in the water and not floating on the surface.

So how can you break down this surface tension? Well you add a detergent such as washing up liquid. Detergents love both water and grease - the detergent molecules have one side of them that attaches to water and one side of them that attaches to grease - so when you put detergent in your washing up it holds the water and grease together so the grease can be washed away with the water.

Surface tension can also be fun to mess around with - have a look at how detergents can power a boat.

Or amaze your friends with this impressive physics trick using surface tension (link to video or written instructions) - do not put detergent in this one otherwise you'll get your feet wet!

Try more physics tricks from our Physics to Go physics tricks pack.