The dielectric loss factor relates to the inability of molecules in the insulating fluids to reorient themselves with an alternating electric field. This ability is dependent on the temperature of the sample, the size of the molecules involved, and their polarity. It is also dependent on the frequency of the alternating field. The dissipation factor and the permittivity are both affected by the molecular size, composition, and relative orientation of functional groups within the molecules. In general within a series of similar molecules, the permittivity will increase as the molecular weight increases. The above-described factors are electrical characteristics of the insulating fluid and can be used to monitor the quality of the oil with regard to deterioration in use and for the presence of contaminants.