Hello Student ,

Beer Lambert's Law is actually a combination of Two laws

Lambert's Law - When a monochromatic light ray of initial intensity is passed through a colored solution, the intensity of transmitted light will decrease exponentially with increase in path length of light i.e , diameter of the cuvette.

Beer's Law - When a monochromatic light ray of initial intensity is passed through a colored solution, the intensity of transmitted light will decrease exponentially with increase of light absorbing particles i.e, nothing but concentration of the particles  to be measured.

It can also be expressed in the formula shown below

Hello!

Beer - Lambert law states that the quantity of light absorbed by a substance dissolved in a fully transmitting solvent is directly proportional to the concentration of the substance and the length of the path of the light through the solution.

The Mathematical Expression is :

A=ε×C× L

Where ;

A is the Absorbance

C=Concentration of the substance

L= Length of the path

ε= Molar Extintion Cofficient .

Hope this Helped:)