(9) Internal Revenue Code means the Internal Revenue Code of 1986 in effect for the federal tax year beginning on January 1, 2007, not including any changes made by federal law after that date, and any regulations adopted under that code applicable to that period.
Absorbance is the negative logarithm of the percent transmittance divided by 100. A spectrophotometer can be set to measure either the percent transmittance or the absorbance of a solution. In lab, you will be using a spectrophotometer called the Spectronic 20 or Spec 20 to measure absorbance.
A spectrophotometer measures the intensity of a light beam before and after it passes through a sample and compares these two intensities. The Spec 20 reports two types of measurements: percent transmittance and absorbance.Percent transmittance is the ratio of the intensity of the light passing through the sample to the intensity of the light shining on the sample multiplied by 100%.Absorbance is the log of the transmittance. The Spec 20 can measure absorbance and transmittance over a range of wavelenghts.You must select a wavlength and calibrate the instrument at that wavelength before making any measurements.bsorbance is the log of the transmittance. The Spec 20 can measure absorbance and transmittance over a range of wavelenghts. You must select a wavlength and calibrate the instrument at that wavelength before making any measurements.