Publisher Summary The interaction of light with particles in solution can cause turbidity because it is scattered in various directions. Such light scattering is studied to obtain the information about the size and shape of the solute molecules. Wavelengths other than those involved in absorption—either by the solutes or by the solvent—are preferred. Current instrumentation improvements involve the use of laser beams as the light source in place of the more traditional lamps. Lasers offer a greater intensity and a more sharply defined wavelength, and allow bringing the photometer cell closer to the trap for unscattered light. The technique weighs the information in favor of the larger particles in the solution. A way to look at light scattering data is by measuring the turbidity. If the particles are big enough, they can cause a measurable decrease in the incident light.