1A UU U.T ntOT dm In B. A certain substance in a cell of length /l absorbs 10 per cent of the incident light. What fraction of the incident light will be absorbed in a cel five times as long ?
Assuming an exponential law of the light absorption like L=L0*exp(-a*x) one gets
0.9 = exp(-a*l) from which one obtains fraction of light passing the thickness 5l as exp(-a*5l) = (...