Light Absorption by a Solution

When a solution of copper sulfate is placed in the path of the beam, the color of the light that passes through is blue, the same as the color of the solution. As it passes through the solution, the beam of light is only faintly visible from the side, which means there is little scattering of the light beam by this solution. This is consistent with the copper and sulfate ions of this solution being smaller than the wavelengths of visible light - too small to effectively scatter light.