Photometry: Colorimeter and Spectrophotometer
Photometry deals with the study of phenomenon of light absorption by molecules in solution. The specificity of a compound to absorb light at a particular wavelength is useful in quantitative measurements. When a light beam of particular wavelength is passed through a solution, some amount of light is absorbed by the solution, and consequently the intensity of light that comes out of solution is diminished. The phenomenon of absorption of light by a solution follows Beer-Lambert’s law. Beer’s law states that amount of transmitted light decreases exponentially with increase in the concentration of absorbing medium. Lambert’s law states that amount of transmitted light decreases exponentially with increase in thickness of absorbing medium.