What happens to absorbance when volume is halved?

When the volume of a solution is halved, the concentration of the solute in that solution typically doubles, assuming no solute is lost and the total mass remains constant. According to Beer-Lambert Law, absorbance is directly proportional to concentration; thus, halving the volume will generally result in an increase in absorbance. This means that if you measure the absorbance after halving the volume, you would expect it to be higher than the original measurement.