"Given that the maximum molar absorption coefficient of a molecule containing a carbonyl group is 30 dm3 mol-1 cm-1 near 280 nm, calculate the thickness of a sample that will result in (a) half the initial intensity of radiation, (b) one-tenth the initial intensity." My attempt: What is confusing me is I feel like I need the concentration to be given, but it's not. A = -log(T) = εbc where T is transmittance, ε is molar absorptivity, b is path length, and c is concentration. I am understanding that the problem is looking for the path length, but I'm not completely sure about this. I would do this for part A. -log(0.5) = (30)*b*c and solve for b. how can i solve this? what am i missing?