What is the role of a dielectric in a capacitor?

The role of a dielectric in a capacitor is to increase the capacitance. When a dielectric material is inserted between the plates of a capacitor, it enhances the capacitor's ability to store electrical energy. This occurs because the dielectric reduces the electric field between the plates, allowing more charge to be accumulated for a given voltage. The dielectric constant of the material determines how much more capacitance can be achieved compared to a capacitor with a vacuum or air between the plates.

In practice, using a dielectric material with a high dielectric constant can significantly boost the capacitance, allowing for smaller and more efficient capacitor designs in electronic circuits. This attribute is fundamental to many applications, such as tuning circuits, filtering applications, and energy storage systems, where maximizing capacitance is essential for performance.