When light shines on an object, it can either be absorbed, reflected, or passed through. A spectrophotometer assesses the amount of light absorbed across the UV and visible ranges. It compares the intensity of light transmitted through the sample to the initial intensity of the light source. Utilizing the Beer-Lambert Law, which correlates the amount of light absorbed to the concentration of the sample and the path length, the spectrophotometer determines the concentration of particular analytes in the sample.