Dielectric materials in capacitors can be likened to a: B: fluid that alters flow in a pipe, A: filter that removes impurities from air, C: sponge that absorbs water, D: resistor that limits current flow. How do dielectric materials affect charge flow in capacitors?

Dielectric materials act like a sponge that absorbs the electric field, so the field inside the capacitor is reduced while the capacitor can store more charge. Because the field is weaker, the same voltage can push more charge onto the plates, so the capacitance increases. In other words, the dielectric “holds” the electric flux, allowing the capacitor to store more charge at the same voltage. For example, a capacitor with a water layer between its plates can hold twice as much charge as an identical capacitor with air, because the water’s dielectric constant is about 80. Thus, dielectrics increase charge storage by reducing the internal electric field.