I am conducting a number of experiments for my Physics EEI, in which UV radiation levels are tested after passing through different types and thicknesses of sunscreens. From what I understand, the basic idea behind sunscreen is that some of the UV rays are reflected/scattered before reaching the skin, while others are filtered to reduce the number of rays reaching your skin.
As part of the investigation I must back my results up with scientific/mathematical evidence, but I can't figure out what quite it is I'm looking for. Any help would be appreciated.
I apologise if this question is inappropriate or in the wrong section.