AS Level particle physics help!?

Question

rayleigh's oil drop experiment

if you know the volume of the oil drop when it's dropped onto the water, and you know that when it spreads out, the drop is one molecule thick, how do you work out the size of one oil molecule?

And what measurements would you have to take to work it out?

Answer 1

The measurements you need are the volume of the oil drop and the area it covers.

Since the oil is 1 molecule thick on the surface of the water, then the volume of the oil is the the area of the water time times the height of one molecule.

If you know the volume of the drop you just need to divide the volume of the drop by the area the oil covers to give you the diameter of the oil molecules.