Capacitors and Supercapacitors Vocabulary

Vocabulary flashcards covering the definitions, formulas, units, types, and applications of capacitors and supercapacitors.

Capacitor

A two-terminal electrical device that stores electrical energy in the form of an electrostatic charge within an electric field.

Dielectric

An insulating material or vacuum filling the space between two electrical conductors (plates) in a capacitor.

Capacitance

The ability of a capacitor to store electric charge, defined as the ratio of the charge ($Q$) to the potential difference ($V$) between the conductors: $C = \frac{Q}{V}$.

Parallel Plate Capacitor Circuit

A circuit setup where a DC voltage source $V$ is connected across two conducting plates (Plate I and Plate II) separated by a dielectric material.

Charging Phase

The process where connecting a capacitor to a DC voltage source causes electrons to accumulate on one plate (becoming negatively charged) while the other loses electrons (becoming positively charged), forming an electric field across the dielectric.

Discharging Phase

The process where connecting the charged plates of a capacitor to an external load allows current to flow from the positive plate to the negative plate until all stored charges are dissipated.

Energy Stored in a Capacitor

The electrical potential energy stored due to the separation of opposite charges, calculated using the formula $E = \frac{1}{2} C V^2$, where $E$ is energy in joules, $C$ is capacitance in farads, and $V$ is voltage in volts.

Farad ($\text{F}$)

The standard SI unit of capacitance.

Millifarad ($\text{mF}$)

A sub-unit of capacitance equal to $10^{-3}\,\text{F}$.

Microfarad ($\mu\text{F}$)

A sub-unit of capacitance equal to $10^{-6}\,\text{F}$.

Nanofarad ($\text{nF}$)

A sub-unit of capacitance equal to $10^{-9}\,\text{F}$.

Picofarad ($\text{pF}$)

A sub-unit of capacitance equal to $10^{-12}\,\text{F}$.

Types of Capacitors

Various physical capacitor configurations, including super capacitors, tantalum capacitors, ceramic capacitors, film capacitors, polyester capacitors, polypropylene capacitors, silver mica capacitors, and variable capacitors.

Supercapacitor

Also known as an ultracapacitor, a high-capacity capacitor with capacitance values up to $2\,\text{kF}$ and fast charging times ($1\text{ to }10\,\text{seconds}$), bridging the gap between conventional electrostatic capacitors and rechargeable chemical batteries.

Electrostatic Double-Layer Capacitors (EDLCs)

A category of supercapacitors consisting of carbon electrodes, a separator, and an electrolyte, which stores energy through physical electrostatic charge adsorption and desorption across a charge separation distance of $0.3\text{ to }0.8\,\text{nm}$.

Pseudo-Capacitors

Electrochemical supercapacitors utilizing metal oxide or conducting polymer electrodes that store electrical energy via electron charge transfer through reduction-oxidation (redox) reactions at or near the electrode surface.

Hybrid Capacitors

Supercapacitors that combine asymmetric electrodes (one electrostatic and one electrochemical) to store energy using both physical adsorption and chemical redox intercalation.

Lithium-Ion Capacitor

A specific example of a hybrid capacitor that utilizes asymmetric electrodes.

DRAM (Dynamic Random Access Memory)

An IT and computing application that utilizes capacitors to store binary data bits.