Voltage, Current, and Resistance Vocabulary

Vocabulary flashcards generated from Chapter 2 (Voltage, Current, and Resistance) covering basic atomic principles, electrical units, circuit components, and measuring instruments.

Bohr Atom

An atomic model useful for visualizing atomic structure, consisting of a positively charged nucleus containing protons and neutrons, with negatively charged electrons in discrete shells.

Atomic Number

The number of protons in the nucleus of an atom, which determines the particular element.

Valence Shell

The outermost electron shell of an atom.

Valence Electron

An electron located in the outermost shell (valence shell) of an atom.

Conductor

A material that has many free electrons due to its atoms having 1 to 3 valence electrons (less than four), allowing easy movement of electrons.

Insulator

A material in which the atoms' outermost shell electrons are tightly bound (typically 5 to 8 valence electrons) and not free to move easily from atom to atom.

Semiconductor

A material with four valence electrons that is neither a good conductor nor a good insulator.

Charge

An electrical property of matter that exists because of an excess or a deficiency of electrons, symbolized by $Q$.

Coulomb

The unit of electrical charge ($Q$), where $1\,\text{Coulomb} = 6.25 \times 10^{18}$ electrons.

Positive Ion

An atom or group of atoms created by removing electrons, resulting in a greater number of protons than electrons.

Negative Ion

An atom or group of atoms created by adding electrons, resulting in a greater number of electrons than protons.

Voltage

The amount of energy per charge available to move electrons from one point to another in an electric circuit, defined equationally as $V = \frac{W}{Q}$.

Potential Difference

The difference between two points having different charge levels that has the potential to move electrons from an area of excess electrons to an area of electron deficiency.

Electromotive Force (emf)

The force that moves electrons from one place to another in a circuit.

Volt

The basic unit of potential difference or electromotive force, defined as the potential difference between two points when one joule of energy is used to move one coulomb of charge from one point to the other.

Daniell Cell

A single-cell battery consisting of a copper-zinc ($Cu\text{-}Zn$) wet cell that utilizes an oxidation-reduction reaction to transfer electrons.

Free Electrons

Electrons that have been bumped out of their atomic orbits and are attracted to fill vacant electron spaces in nearby atoms.

Electron Flow Direction

The direction in which electrons flow from the negative terminal of a source through the external circuit toward the positive terminal.

Conventional Current Direction

The convention where current is considered to flow from a point of higher potential ($+$) toward a point of lower potential ($-$).

Current

The net amount of electrical charge that flows past a point in a unit of time ($I = \frac{Q}{t}$).

Ampere

The unit of electrical current, defined as one coulomb of charge flowing past a point in a circuit in one second ($1\,\text{A} = 1\,\text{C/s}$).

Resistance

The opposition to electron movement or current flow in an electrical circuit, measured in ohms ($\Omega$).

Ohm

The unit of electrical resistance that limits current to one ampere when one volt of electromotive force is applied.

Conductance

The ability of a circuit to allow current, which is the reciprocal of resistance ($G = \frac{1}{R}$).

Siemens

The unit of measurement for conductance, symbolized by $\text{S}$.

Resistor Tolerance

The range of acceptable resistance values for a resistor, indicated by a band on the resistor.

Potentiometer

A three-terminal variable resistor.

Rheostat

A two-terminal variable resistor.

Resistivity

The resistance in ohms of a given material per standard length and cross-sectional area, symbolized by $\rho$ (Rho).

American Wire Gauge (AWG)

A standardization system for conductor wire size based on wire diameter.

Electric Circuit

An interconnection of electronic components designed to produce a desired result, consisting of a voltage source, a path, and a load.

Pole

The movable arm of a switch.

Throw

The number of contacts that are affected by a single switch action.

Digital Multimeter (DMM)

A multipurpose electronic test instrument used to measure voltage, current, and resistance.

Analog Multimeter (VOM)

A volt-ohm-milliammeter that uses a needle scale to measure voltage, current, and resistance.

Ground

The common or reference point in an electrical circuit.