“…The ratio, I/I o, is generally defined as transmittance. As per Beer‐Lambert law, the absorbance of light by the sample is deduced from the transmittance, as given in Equation , which is also proportional to the path length, concentration, and absorptivity of the given sample as follows: where A refers to absorbance, T refers to transmittance, ϵ refers to molar absorptivity, c refers to the concentration of the sample, and l refers to the length of the light path, which is equal to the width of the cuvette. The same absorbance, A , is recorded on the detector after the transmitted light passed through the mirror and rotating disc comparing with the reference.…”