Surface Tension of Rainwater

Surface tension is a property of liquid where liquid surface at rest contract into minimum possible area. Surface tension has a tendency to create a stretched membrane of liquid on which heavy objects like needle can float or waterspider can walk. Aim of the research is to estimate value of surface tension of rainwater and compare with the standard value of surface tension of water at temperature 25℃. Surface tension of rainwater is calculated experimentally by using capillary-rise method in laboratory. In this experiment one capillary is inserted in liquid and the rise of liquid in the capillary is measured using travelling microscope from the level of water in beaker. In this research, measurement of radii, height of liquid in capillary and surface tension are carefully analyzed. Researcher found that surface tension of rainwater is greater than the standard value of surface tension of water at 25℃. The height of liquid depends on radii of capillary, as radii increases height of liquid column inside the capillary decreases. It is observed that as height of liquid column in capillary decreases, the surface tension of rainwater increases.