Measuring Concentration With Invisible Light

You can calculate exactly how much of a substance is dissolved in a liquid simply by measuring how much light it blocks. The darker the color appears to our eyes, the more molecules are crowding the solution.

This principle works because light particles collide with molecules as they travel through a liquid. By shining a specific wavelength of light through a sample, scientists can measure how much energy is absorbed. This simple relationship allows researchers to analyze everything from clean water supplies to the concentration of medicine in blood samples. It turns light into a precise ruler for the invisible contents of a mixture.