Absorption takes place and the beam of radiation leaving the sample has radiant power P .
If all the light is absorbed, then percent transmittance is zero, and absorption is infinite. We will express this measurement in centimetres. The reason why we prefer to express the law with this equation is because absorbance is directly proportional to the other parameters, as long as the law is obeyed. We are not going to deal with deviations from the law. We will look at the reduction every 0.2 cm as shown in the diagram below.