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Thread: cappilary action between pieces of glass. how?

  1. #1 cappilary action between pieces of glass. how? 
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    I am experimenting with strips of glass trying to see how high it can pull water.

    To test if a cappilary vessel could be made from 2 pieces of glass I did this experiment:
    I have used 2 small piece of glass 10 cm in height. I placed some hair in between to make sure there was a little space for a cappilary. Then put them into a pan with water. I had a piece of sponge against the ridge at the top and hanging down below the waterline next to the pan. The water traveled slowly through the sponge but it was surely getting the water through. So 2 pieces of glass close to eachother can be used as a cappilary vessel.



    I then tried getting the water higher put but using 2 pieces of glass 30cm high, 15 cm width. again with some single hairs in between as a spacer. Somehow I can't get the cappilary going again.



    So I took the 2 piece apart and noticed the top part of the glass was not wet.





    So is there an obvious limit? What would be the best width in between the glass?

    So I wonder:

    - how width in between the glass plates for best/highest cappilary action?

    Any other ideas, links and comment on this subject are very welcome.
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  3. #2  
    Forum Ph.D. Cat1981(England)'s Avatar
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    I believe that the limit for the capillary action on earth is around 360 feet which is why trees will never grow higher then that despite a natural tendency to grow higher then the competition.

    You could try using glass with less width?


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  4. #3  
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    In the above setup I had only mirror-glass at hand. I now got some bits of transparent glass (nice because now i can actually see what goes on between the glass). Turns out that it only goes about 10-14 cm up. I would like to know why with the mirror glass water went up 25 cm. The mirrorglass is quite thick, so maybe the steardyness of the glass has some effect. And the mirror was wider. As cappilary action works with atmospheric pressure, maybe distance to the openings on the side of the glass are of some importance.

    Anyone got experience with this to share?
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  5. #4  
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    i don't have any experience but like you were saying if you closed the gap in the sides it could make a difference - the water might end up running up then get pushed out so it might even work to seal it?

    where the hairs any longer in the previous experiment as they would act like a sponge?

    where the atmospheric conditions different (including temperature) during the periods of your experiment - could this account for some of it?
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  6. #5  
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    Capillary action depends on the surface tension of the liquid (water in this case) and the angle of contact between the surface of the water and the solid surface. The height to which the water is raised can be calculated from the vertical component of the force due to surface tension. At equilibrium, this force is balanced by the weight of water below the surface. By reducing the gap,you are reducing this weight and so the water rises higher. If you were to halve the gap, the water should rise twice as high.
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