Glossary
Capacitance (C)
A measure of a capacitor's ability to store electric charge per unit of potential difference across its plates. It is a fixed value for a given capacitor.
Example:
A large capacitance value means the capacitor can hold a significant amount of charge even at a relatively low voltage.
Capacitor
An electronic component designed to store electrical charge and energy in an electric field.
Example:
A camera flash uses a capacitor to quickly release a burst of light.
Charge Storage
The process by which a capacitor accumulates equal but opposite amounts of electric charge on its two plates when a voltage is applied across it.
Example:
A fully charged phone battery relies on efficient charge storage within its internal components.
Conductive Material
A substance that allows electric charge to flow easily through it, typically used for the plates of a capacitor.
Example:
Copper wires are excellent examples of conductive material due to their low electrical resistance.
Dielectric Insertion
The act of placing a dielectric material between the plates of a capacitor, which typically increases its capacitance and reduces the electric field for a given charge.
Example:
Performing a dielectric insertion into an existing capacitor can make it more efficient at storing energy without changing its physical dimensions.
Dielectric Material (κ) / Dielectric Constant
An insulating substance placed between the plates of a capacitor to increase its capacitance by reducing the electric field strength. The dielectric constant (κ) quantifies this effect.
Example:
Using paper as a dielectric material in a capacitor can significantly boost its charge storage capacity compared to an air-filled one.
Electric Field (between plates)
A region of space between the capacitor plates where a charged particle would experience an electric force, directed from the positive to the negative plate.
Example:
The uniform electric field inside a capacitor can accelerate electrons, similar to how gravity accelerates objects.
Electric Field Strength (E_C)
The magnitude of the electric field between the plates of a capacitor, representing the force per unit charge.
Example:
A higher electric field strength between capacitor plates means a greater force on any charge placed within it.
Electric Potential Energy (U_C) / Energy Stored in a Capacitor
The work done to charge a capacitor, which is stored as potential energy within its electric field and can be released when the capacitor discharges.
Example:
A defibrillator stores a large amount of electric potential energy in its capacitors to deliver a life-saving shock.
Parallel-Plate Capacitor
A common type of capacitor consisting of two flat, parallel conductive plates separated by a small distance, typically with a dielectric material between them.
Example:
Many circuit diagrams represent a parallel-plate capacitor with two parallel lines.
Permittivity of free space (ε₀)
A fundamental physical constant representing the ability of a vacuum to permit electric fields. It is used in equations for electric fields and capacitance.
Example:
The permittivity of free space is a constant value used in Coulomb's Law to determine the force between charges in a vacuum.
Plate Area (A)
The surface area of one of the conductive plates in a parallel-plate capacitor.
Example:
Increasing the plate area of a capacitor allows it to store more charge, similar to how a larger bucket holds more water.
Plate Separation (d)
The distance between the two conductive plates of a parallel-plate capacitor.
Example:
Reducing the plate separation in a capacitor strengthens the electric field and increases its capacitance.
Polarization (of dielectric)
The process where the molecules within a dielectric material align themselves in response to an external electric field, creating an internal opposing electric field.
Example:
When a strong electric field is applied, the atoms in a dielectric undergo polarization, causing their electron clouds to shift slightly.