Determination of Surface Tension by Pendant Drop Method: Effect of Tip]s Diameter

This research aims design for theexperimental setup to determine surface tension of liquids by the pendant 
drop method. This experiment was designed for student in the upper secondary level or higher education. 
Photographs of water droplet were taken, and Young-Laplace equation was applied. The setup consists of a syringe with its tip straight cut for diameters of 0.60, 0.80 and 1.2 mm. A lamp and smartphone were set to take photographs which are analyzed by ImgaeJ program. A drop of distilled water was formed at the tip. The pendant drop method requires measuring diameter. The value of the diameter of the drop at its widest part was DE and the value of the diameter of in a position at vertical distance D_E from the lowest end was D_S . From the results, the diameter of the dropper's tip does not affect the surface tension of the distilled water. But the shape of the water drop affects to the surface tension. The difference between D_E
and DS of the water drops from various tip's diameters should be in the range of 0.080 – 0.10 mm. In order to obtain accurate surface tension, the water drop must maintain its shape before it leaves the tip of the dropper that the balance between surface tension and the gravitational force. Finally, the tip's diameter of dropper and the volume of distilled water do not affect the surface tension