The Polarizability of Normal - and Cyclo - alkanes

The additivity of the molecular dipole polarizability was established already in the 1920s. However, whereas the magnetizability could easily be ratio- 

The behavior of the polarizability of the n-alkanes may be rationalized with reference to the simple particle-in-a-box model. In this model, the polarizability increases as the fourth power in the length of the box, which implies that the polarizability per unit length (i.e., the differential polarizability) increases as the third power in the length of the box. Obviously, in the n-alkanes, the electrons do not at all behave according to this simple model, but we may still attribute the increasing differential polarizability of the n-alkanes to a more pronounced delocalization of the electrons in the longer chains, as the electrons become more loosely attached to the system. As the chain grows, this effect becomes less important and the differential polarizability becomes constant. 

in the n-alkanes, there is a small but noticeable increase in the differential polarizability with the chain length, we would expect this effect to be more pronounced in conjugated systems, where the delocalized 7r-electrons 

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