Introducing a dielectric into a capacitor decreases the electric field, which decreases the voltage, which increases the capacitance. A capacitor with a dielectric stores the same charge as one without a dielectric, but at a lower voltage. ... Voltage and capacitance are inversely proportional when charge is constant.

How does dielectric material increase capacitance?

(a) The molecules in the insulating material between the plates of a capacitor are polarized by the charged plates. This produces a layer of opposite charge on the surface of the dielectric that attracts more charge onto the plate, increasing its capacitance.

Why do dielectrics generally increase capacitance?

The dielectric placed between the plates of the capacitor reduces the electric field strength between the plates of the capacitor, this results in a small voltage between the plates for the same charge. The capacitor stores more charge for a smaller value of voltage. Therefore the capacitance increases.