Final answer:
Introducing a dielectric material between the plates of a charged conductor decreases the electric field between the plates, as it becomes polarized and generates an opposing electric field. This results in a reduced voltage for the same charge, leading to an increased capacitance.
Step-by-step explanation:
When a dielectric material is introduced between the plates of a charged conductor, the electric field between the plates is decreased. This phenomenon occurs because the dielectric material becomes polarized in the presence of an electric field. The polarization means that the material itself generates an electric field that opposes the original electric field caused by the charged plates of the capacitor. Therefore, the overall electric field between the plates is weakened.
Considering a parallel plate capacitor that's been charged and then disconnected from its power source, the introduction of a dielectric does not change the amount of charge on the plates but affects the potential difference across them. As the dielectric strength of the material suggests, it can withstand a certain electric field before breaking down, and within those limits, it effectively reduces the field strength between the plates.
The reduced electric field due to the dielectric also leads to a decrease in voltage between the capacitor's plates (V = Ed, where E is the electric field, and d is the distance between plates), and as a result, for the same amount of charge, the capacitance is increased because capacitance C = Q/V. The ability of a dielectric to increase capacitance is described by its dielectric constant, which quantifies how effectively the material reduces the electric field within a capacitor.