# Surface Tension?

• derekmohammed

#### derekmohammed

Hi,

Just a quick question:

How do you meausre surface tension of a liquid? WHat meathods are used and how do the units reflect the data.

Thanks

Derek Mohammed

You might have a look at the following site:
http://www.kruss.info/techniques/methods_overview_e.html#Wilhelmy_Plattenmethode [Broken]

Here is some further comments on the Du Nuoy ring method and Wuilhelmy plate method:
http://www.ksvinc.com/sigma703.htm [Broken]

Essentially it seems, each of these methods relies on relating the force needed to detach a simple geometric object from the liquid surface to the surface tension.

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What do the units stand for? mN/m? Newton metres/ Metres??

Thanks

mN=10^-3N and the denominator is in metres

Presumably you could measure the velocity and wavelength of the "ripples" in a liquid to measure its surface tension, since it provides the restoring force for some waves on the surface. I'm sure there are other ways, though.

Numerically Surface Tension (T):

$T= \frac{F}{l}$

Infact, if you consider a unit length line on the surface of the water and measure the force on it from water on one side will give you Surface Tension. But that's not the 'experimental
method.