Intensity of light source Io = 1000 counts Intensity after absorption I = 392 counts Transmittance T = (I/Io) = 392/1000 = 0.392 Absorbance A = -log T = -log(0.392) = 0.407 Solution Intensity of light source Io = 1000 counts Intensity after absorption I = 392 counts Transmittance T = (I/Io) = 392/1000 = 0.392 Absorbance A = -log T = -log(0.392) = 0.407.