Imaging surface water waves for the determination of surface tension and spatial attenuation

We propose the use of the image analysis technique to determine the surface tension of water and the attenuation coefficients of surface water waves in terms of frequency. Tap water from two different locations is used in our experiments. Water waves are continuously generated at various frequencies in a ripple tank by a plastic blade driven by a function generator. Images of the water waves are then captured by a digital camera and analyzed by using Tracker. As a result, we obtain the surface tension of water at 25 degrees C from both locations that are in good agreement with those resulting from the capillary rise technique. In addition, a linear relationship between the attenuation coefficient of the water waves and driven frequencies, ranging from 40 to 90 Hz, can be observed. Our results indicate that the greater the surface tension the longer distance the water wave takes before its amplitude decreases to 1/e of its original value. This work brings forward a relatively simple technique that can be applied to determine the surface tension and attenuation coefficients of surface water waves in a ripple tank with notable results.