List two conditions necessary for accurate quantitative measurements using Beer-Lambert law and UV-Vis spectroscopy. For each condition you list give a brief explanation.

Monochromatic Light: The Beer-Lambert law assumes that the light passing through the sample is monochromatic, meaning it consists of only one wavelength. This is important because different wavelengths of light are absorbed differently by different substances. If the light is not monochromatic, the measurement could be skewed by the presence of other wavelengths that are absorbed to a greater or lesser extent.

Constant Path Length: The Beer-Lambert law also assumes that the path length of the light through the sample is constant. This is because the amount of light absorbed by a substance is directly proportional to the path length of the light through the substance. If the path length varies, the absorbance measurement will not accurately reflect the concentration of the substance in the sample.