Dielectric

Definition

A dielectric is a non-conductive material that, when placed between the plates of a capacitor, increases its capacitance by reducing the electric field strength. This effect occurs due to polarization within the dielectric material.

5 Must Know Facts For Your Next Test

1. Dielectrics increase the capacitance of a capacitor by a factor equal to their dielectric constant (κ).
2. The dielectric constant is always greater than 1 for any material used as a dielectric.
3. When a dielectric is introduced into a capacitor, it reduces the potential difference for the same amount of charge stored.
4. Dielectrics can be solid, liquid, or gas and are chosen based on their dielectric strength and thermal stability.
5. Introducing a dielectric into an isolated capacitor (one not connected to a battery) decreases the voltage across its plates.

Review Questions

• How does inserting a dielectric between the plates of a capacitor affect its capacitance?
• What happens to the voltage across an isolated capacitor when a dielectric is introduced?
• Why is the dielectric constant always greater than 1 for materials used in capacitors?

Related terms

Capacitance: The ability of a system to store an electric charge, defined as the ratio of stored charge (Q) to potential difference (V), given by $C = \frac{Q}{V}$.

Dielectric Constant: A dimensionless measure of how much an insulating material can increase the capacitance of a capacitor relative to vacuum; also known as relative permittivity.

Polarization: The alignment of dipole moments in an insulating material when exposed to an electric field, which reduces the overall field within the material.