Optical activity is a property exhibited by certain substances that rotate the plane of polarized light passing through them. This phenomenon arises due to the interaction of chiral molecules with plane-polarized light, causing a rotation in its plane of vibration. Enantiomers, non-superimposable mirror images of each other, often display optical activity. The measurement of optical activity is quantified using a polarimeter. In a polarimeter, plane-polarized light passes through a sample, and the extent of rotation is measured. The specific rotation (α) is the observed rotation corrected for concentration and path length, providing a characteristic value for a given compound.