When a voltage is applied between the electrode and the water, the interfacial tension between the water and the coating changes.
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Contact angle goniometers can also determine the surface tension for any liquid in gas or the interfacial tension between any two liquids.
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Also included in this book are the measurement techniques to obtain activity coefficients, interfacial tension, and critical parameters.
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If the difference in densities between the two fluids is known, the surface tension or interfacial tension can be calculated by using the pendant drop method.
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Young's equation describes the contact angle of a liquid drop on a plane solid surface as a function of the surface free energy, the interfacial free energy and the surface tension of the liquid.