Tabor and Wintertons Experiment

For example, in the laboratory conditions, air of 50-80% relative humidity was used. This caused a thin layer of moisture to be adsorbed on the mica. By measuring the fine multiple beam fringes before and after moisture adsorption, it was deduced that the total thickness of water between the two foils was 0.7 nm. In order to perform an adhesion experiment using this apparatus, two precautions had to be taken the apparams had to be protected from vibrations so the work was done at night on vibration isolators also, the surfaces had to be 

For jump distances between 5-15 nm, the results fitted the Hamaker theory which states that the attractive van der Waals force is proportional to cylinder diameter and inversely proportional to the square of the gap. The Hamaker constant was found to be 10 J. These experiments were the first to reveal the true van der Waals forces at close approach. Previous tests had only shown the weaker, retarded forces which apply for gaps larger than 20 nm. These theories will be considered in Chapter 5. 

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