# Electrical definitions and terminology

On this page, we are listing common electrical terms used in electricity. These electrical-related words and definitions list will help you to know the technical side of electricity and electrical engineering.

Table of Contents

## Electrical definitions and terminology

Electrical terms are important. You need to improve your vocabulary knowledge to be a technical person. This small glossary will help you understand the terminology.

**Admittance **

**Alternating Current (AC)**

An electric current that reverses its direction many times a second at regular intervals.

**Ampere (A)**

A unit of measure for the intensity of an electric current flowing in a circuit. One ampere is equal to a current flow of one coulomb per second.

**Amplitude**

The total variation of a waveform. Amplitude can be expressed as a peak value, peak-to-peak value, or effective value.

**Branch Circuit**

A single circuit carrying electrical current to office furniture and equipment. It consists of conductors connected between the building’s electrical service panel and the electrical outlets.

**Capacitance**

The ability of a body to store an electrical charge. Measured in farads as the ratio of the electric charge of the object (Q, measured in coulombs) to the voltage across the object (V, measured in volts).

**Circuit**

A complete path for electrical current flowing from the building power source to the equipment being powered and back to the power source

**Conductor**

Any material where electric current can flow freely. Conductive materials, such as metals, have relatively low resistance. Copper and aluminum wire are the most common conductors.

**Corona**

A corona discharge is an electrical discharge brought on by the ionization of a fluid such as air surrounding a conductor that is electrically charged. Spontaneous corona discharges occur naturally in high-voltage systems unless care is taken to limit the electric field strength.

**Current (I)**

The flow of an electric charge through a conductor. An electric current can be compared to the flow of water in a pipe. Measured in amperes.

**Cycle**

The change in an alternating electrical sine wave from zero to a positive peak to zero to a negative peak and back to zero.

**Dielectric**

A material that does not allow free flow of electric current.

**Direct Current (DC)**

An electric current that flows in only one direction.

**Electrolyte**

Any substance that, in solution, is dissociated into ions and is thus made capable of conducting an electrical current. The sulfuric acid-water solution in a storage battery is an electrolyte.

**Electromagnetic Interference (EMI)**

An electrical, magnetic, or electromatic, e.g. radio interference that causes an undesirable response, degradation, or failure in electronic equipment.

**Electron**

A tiny particle that rotates around the nucleus of an atom. It has a negative charge of electricity.

**Farad**

A unit of measure for capacitance. One farad is equal to one coulomb per volt.

**Filter**

A circuit that selectively alters a signal based on its frequency components.

**Frequency**

The number of cycles per second. Measured in Hertz. If a current completes one cycle per second, then the frequency is 1 Hz; 60 cycles per second equals 60 Hz.

**Ground**

The reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth.

**Hall effect**

The phenomenon whereby charge carriers are displaced perpendicularly to their drift velocity when current flows in the presence of a magnetic field.

**Henry**

A unit of measure for inductance. If the rate of change of current in a circuit is one ampere per second and the resulting electromotive force is one volt, then the inductance of the circuit is one henry.

**Hertz**

A unit of measure for frequency. Replacing the earlier term of cycle per second (cps).

Horsepower A unit of power. Horsepower is abbreviated “HP.” 1 horsepower is equal to 746 watts.

Electrical terms I-M

**Impedance**

The measure of the opposition that a circuit presents to a current when a voltage is applied. Impedance extends the concept of resistance to AC circuits and possesses both magnitude and phase, unlike resistance, which has only magnitude.

**Inductance**

The property of a conductor by which a change in current flowing through it induces (creates) a voltage (electromotive force) in both the conductor itself (self-inductance) and in any nearby conductors (mutual inductance). Measured in henry (H).

**Inductor**

A coil of wire wrapped around an iron core. The inductance is directly proportional to the number of turns in the coil.

**Insulator**

Any material where the electric current does not flow freely. Insulative materials, such as glass, rubber, air, and many plastics have relatively high resistance. Insulators protect equipment and life from electric shock.

**Joule**

The basic unit of electrical energy. 1 Joule is equal to 1 watt-second or the amount of energy transferred in one second when the power is one watt.

**Load**

Describes the amount of power (amps) consumed by an electrical circuit or device. Loads are usually expressed in amps, but sometimes in watts.

**Ohm (Ω)**

A unit of measure of resistance. One ohm is equivalent to the resistance in a circuit transmitting a current of one ampere when subjected to a potential difference of one volt.

**Power**

The rate at which electrical energy is transferred by an electric circuit. Measured in Watts.

**Resistance**

The opposition to the passage of an electric current. Electrical resistance can be compared to the friction experienced by water when flowing through a pipe. Measured in ohms.

**Resistor**

A device is usually made of wire or carbon presents a resistance to current flow.

**Signaling**

Procedures used to control (set up and clear down) calls and connections within a telecommunication network.

**Terminal**

Connection devices are used to terminate or join two conductors.

**Tesla**

A unit of magnetic flux density is equal to one weber per square meter.

**Volt (V)**

A unit measure of voltage. One volt is equal to the difference of potential that would drive one ampere of current against one-ohm resistance.

**Voltage**

An electromotive force or “pressure” causes electrons to flow and can be compared to water pressure which causes water to flow in a pipe. Measured in volts.

**Watt (W)**

A unit of electrical power. One watt is equivalent to one joule per second, corresponding to the power in an electric circuit in which the potential difference is one volt and the current one ampere.

**Wavelength**

The physical distance between the beginning and the end of a cycle in a periodic wave (sine wave or square wave) as it travels through space or a conductor.