What does a spectrophotometer directly compare during its analysis?

A spectrophotometer functions by measuring the amount of light that is transmitted through a solution at various wavelengths. This instrument utilizes the principle of light absorption, which involves passing light through a sample and quantifying how much of that light is absorbed versus how much is transmitted. By comparing the intensity of light before it passes through the sample and after it has exited the sample, the spectrophotometer can determine the absorbance or transmittance at specific wavelengths.

This capability allows scientists to analyze the concentration of specific substances within a sample based on the absorption characteristics of those substances. Different compounds will absorb light differently at various wavelengths, which is essential for identifying and quantifying specific analytes in a solution. Thus, the measurement of light transmission in relation to wavelength is fundamental to the operation of a spectrophotometer and is a key aspect of its analysis.