Linked from
The 29 pages that link to Dielectric, each with the reason it gives.
Electric fieldRelated: Dielectrics modify fields inside capacitors and other materials.
ElectrostaticsRelated: Its polarization changes the field and capacitance of electrostatic systems.
CapacitanceRelated: Polarization changes the field and raises capacitance for a fixed geometry.
MicaRelated: Mica acts as a dielectric in capacitors and other electrical components.
AmberRelated: Amber's insulating nature helps localized charge persist on its surface.
Leyden jarRelated: The glass separates the coatings and strengthens the jar’s charge storage.
FaradRelated: A dielectric changes the capacitance a capacitor can provide in farads.