The Jasco V-730 spectrophotometer operates on the principle of absorbance spectroscopy, where the absorbance of light by a sample is measured as a function of wavelength. The instrument uses a light source to generate a beam of light, which is then divided into two beams: a sample beam and a reference beam. The sample beam passes through the sample, while the reference beam passes through a reference material. The absorbance of the sample is then calculated by comparing the intensities of the sample and reference beams.