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I was observing from many days, how hairs seems to be sticking to water, when made to fall on it. I made an attempt to know what really was going on. I kept a jug of stationary water under the light, and kept my dry hairs combing, to make hairs fell on it. I observed once again that hairs appeared to be sticking to water.


I started thinking about the cause for this observation. At first, what went to my mind was about hairs being rubbed with comb. Usually hairs get positively charged (I don't know exactly. I thought it because plastic becomes negatively charged when rubbed with most of other suitable surface) when rubbed with plastic comb. We also know that water has more negative charge because of oxygen atom (I came to know about this from the diagram of wiki encyclopedia-electronegativity). So, I thought positively charged hairs might be attracted by negative charge nature of water molecules, which might be making hairs to stick with water.


Is it really because of positively charged hairs and negatively charged water molecules, which is making hairs to be sticking to water?

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  • $\begingroup$ While indeed quite polar, water is exactly electrically neutral (as is any substance in most situations without an external potential being applied), so your explanation is not appropriate. Surely this question will be best answered in Physics.SE. $\endgroup$ – Nicolau Saker Neto Nov 9 '13 at 16:43
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    $\begingroup$ @curie can you explain what you ment by "hairs seems to be sticking to water". Whether you mean hairs are sticking together in water! $\endgroup$ – Eka Nov 14 '13 at 17:57
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It doesn't have to do as much with the combing as it does with surface tension. Water on the hair clumps them together, because smaller clumps have more surface area (net surface area) and thus more surface energy. Breaking these large clumps, therefore, requires energy input, which gives us the impression that they "stick" together.

As for sticking to the water individually, that's surface tension again. The surface is able to withstand a bit of weight before collapsing and letting the object drop through. Hairs are oily, and thus hydrophobic. The repulsion potential energy that would be formed / needed when it sinks outweighs the energy required to bend the surface (and get enough tension force to balance gravity). This is how water skeeters work.

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Maybe it's surface tension. See if hairs without electrical charge react the same way.

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