http://www.physics.ox.ac.uk/olympiad/PastPapers.html#ASComp for q8 of the 2007 paper, it says that in water light diffracts less but doesn't light have a small wavelength and water is more dense than air (less gaps between molecules)- shouldn't this mean more diffraction as water molecules and closer together and light has a wavelength comparable to it?
The wavelength must be comparable to the size of the gap, no the medium in which the light passes through. In water, light travels slower than in air or vacuum.
The wavelength must be comparable to the size of the gap, no the medium in which the light passes through. In water, light travels slower than in air or vacuum.