Lambert's Law:
It states that the amount of light absorbed by a substance dissolved in a fully transmitting solvent is directly proportional to the concentration of the substance and the path length of the light through the solution.
Mathematically:
Absorbance (A) ∝ Concentration (c)
Absorbance (A) ∝ Path length (l)
When combined: A ∝ c × l
Beer's Law:
It states that the amount of light absorbed by a substance is directly proportional to the number of molecules in the path of the light.
This implies: Absorbance (A) ∝Concentration (c)
By combining Lambert's and Beer's laws: A = ε × c × l
Where:
A is the absorbance (no units).
ε is the molar absorptivity or molar extinction coefficient (usually in L/(mol·cm)).
c is the concentration of the solute (usually in mol/L).
l is the path length of the cuvette containing the sample (usually in cm).