The Beer-Lambert (Beer's) law and the definitions of transmittance are usually memorized. The attenuation of light as it passes through an absorbing substance is Demonstrating why absorbance is a log function is straightforward and can be connected to radioactive decay and kinetics.
For more details and a related derivation, see the reference document on the Beer-Lambert law.
The spreadsheet displays the following:
The path length of the two curves must be the same since they are plotted on the same chart.
The spreadsheet also has a data entry for Po, which is listed as the number of photons. This could equally well be light power in watts or light intensity. This parameter is included for added flexibility. The Po value does not affect the resulting values of T, %T, or A.
|1||4000 M-1cm-1||2000 M-1cm-1||1e-4 M||1e-4 M|
|2||6000 M-1cm-1||2000 M-1cm-1||1e-4 M||1e-4 M|
|3||6000 M-1cm-1||6000 M-1cm-1||4e-4 M||1e-4 M|
|4||6000 M-1cm-1||6000 M-1cm-1||6e-4 M||1e-4 M|
Determine the maximum absorbance that can be measured for the following experimental parameters:
Determine the minimum absorbance that can be measured for the following experimental parameters:
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