Principle of operation of the colorimeter:A low voltage lamp activated by a constant voltage is the light source. It passes through a designated color filter and a sample solution in the detector (photocell). Then the current produced by the photocell is converted into voltage to display the result on the screen. The front panel switch allows selection of both transmittance (%T) and absorbance (OD).
Simply, the principle of funcionamiento del colorímetro depends on the ley of Beer-Lambert that expresses that the medida of the luz absorbed by a muestra corresponds with the concentration of the solution of the muestra and the length of the recorrido de la luz a través de the solution.