Surface Tension

  • TF9.1 Capillarity

    Using dyed water, see the meniscus formed by water in different diameter tubes.

  • TF9.2 Strength of Surface Tension

    This is comprised of a big ring submerged into a dish of soap water. The ring is suspended by strings leading to a spring, and the dish is supported by a labjack. As the labjack is lowered, the surface tension pulls the ring down and stretches the spring. After some distance, the ring breaks free of the surface. The distance the labjack was lowered can be measured and, knowing the spring constant, the force of the surface tension can be determined.

  • TF9.3  Surface Tension Demos

    This consists of wire frames of objects that will form thin soap films. There is a regular loop and two cubic structures. Also there is a loop with a string in the middle. When one side of the loop is popped, the string stretches out and tried to close up the other side of the loop. Another has three wire sides and a fourth of elastic string. Pulling the string out requires force. When released, the string is pulled in by surface tension, decreasing the area.

  • TF9.4  Water Wedges     WaterWedges

    A thin vertical wedge with a hollow middle is partially filled with dyed water. The class sees that the water is lower at the thicker end and higher at the thin end. This is due to the adhering nature of water. Doing the same with mercury will give the opposite result. This is similar to the positive meniscus of water and negative one of mercury. When using mercury, there is a special block and wax cover to use with the wedge in F25. Please use extreme caution when working with Mercury.