Power Engineering: Matter, Chemistry, Electricity, Magnetism, and Metering

Comprehensive vocabulary flashcards covering introductory concepts in matter, chemical bonding, basic electricity, electromagnetism, and electrical metering devices based on 4th Class Power Engineering notes.

Matter

Anything that has mass and occupies space.

Phase

An individual substance existing in one particular physical state.

Vapour

The gaseous phase of a substance that is normally a liquid or solid under standard room conditions.

Chemical Property

A characteristic describing the way a substance can undergo a change in its chemical composition.

Physical Property

A characteristic used to describe a substance that can be observed without altering its chemical composition.

Intensive Property

A property of matter that does not depend on the amount of matter present, such as boiling point or colour.

Extensive Property

A property of matter that depends directly on the amount of matter present, such as mass and volume.

Sublimation

A physical change of state in which a substance transitions directly from a solid to a gas.

Deposition

A physical change of state in which a substance transitions directly from a gas to a solid.

Homogeneous Mixture

A mixture, also called a solution, that exhibits a uniform composition throughout.

Heterogeneous Mixture

A mixture that exhibits a non-uniform composition and differing physical or chemical properties throughout.

Pure Substance

Any type of matter having a constant chemical composition and displaying identical properties under identical conditions.

Element

A pure substance that cannot be decomposed into simpler forms of matter by chemical means.

Compound

A pure substance formed when two or more elements chemically bond together in fixed proportions by mass.

Atom

The smallest building block of an element that retains the distinct chemical character of that element.

Avogadro's Number

The exact quantity of matter representing one mole of atoms or molecules, equal to $6.022 \times 10^{23}$.

Electronegativity

The relative measure of an atom's ability to attract electrons and fill its outer valence shell.

Covalent Bond

A chemical bond formed when valence electrons are shared between atoms.

Ionic Bond

A chemical bond formed when one or more valence electrons are transferred from one atom to another, resulting in electrostatic attraction between oppositely charged ions.

Metallic Bond

A chemical bond formed when outermost electrons combine to form a cloud of delocalized electrons around metal cations.

Stoichiometry

The branch of chemistry that deals with quantitative calculations involving reactants and products in balanced chemical equations.

Valence Electrons

Electrons located in the outermost energy shell of an atom that participate in chemical bonding and electrical conduction.

Electrical Current

The uniform, orderly flow of free electrons through a conductive material.

Direct Current ($\text{DC}$)

An electrical current that flows continuously in only one direction.

Conventional Current Flow

A model of electrical current flow directed from a higher potential ($+$, positive) to a lower potential ($-=$, negative).

Electromotive Force ($\text{EMF}$)

The electrical pressure or force that causes current to flow in a circuit, measured in volts ($\text{V}$).

Ohm

The unit of electrical resistance, symbolized by $\Omega$, defined as the resistance that allows a current of $1\,\text{A}$ to flow when an $\text{EMF}$ of $1\,\text{V}$ is applied.

Series Circuit

An electrical circuit configuration where components are arranged in a single continuous loop, resulting in identical current throughout all parts.

Parallel Circuit

An electrical circuit configuration containing multiple parallel paths for current, where full line voltage is applied across each branch.

Conductance

The reciprocal of electrical resistance, representing the ease with which current flows through a material, measured in Siemens ($\text{S}$).

Magnetic Flux

The total number of magnetic lines of force occupying a magnetic field.

Permeability

The measure of the ease with which a magnetic field can be established within a material.

Reluctance

The measure of opposition to the establishment of a magnetic field within a material.

Electromagnet

A magnet constructed by coiling a current-carrying conductor around a permeable soft iron core.

Generator Action

The induction of a voltage across a conductor when relative motion occurs between the conductor and a magnetic field.

Motor Action

The mechanical force or thrust exerted on a current-carrying conductor placed within a magnetic field.

Commutator

A split ring mechanical device in a $\text{DC}$ generator or motor that continuously reverses armature connections to maintain unidirectional current in the external circuit.

Slip Rings

Conducting rings connected to the rotating loop of an $\text{AC}$ generator that deliver induced alternating current directly to brushes.

Right Hand Rule for Generators

A rule using the thumb (motion of conductor), index finger (field direction from $\text{N}$ to $\text{S}$), and second finger (induced current direction) to determine generator operation parameters.

Left Hand Rule for Motors

A rule using the thumb (direction of force), index finger (magnetic field from $\text{N}$ to $\text{S}$), and second finger (direction of current) to determine motor action.

Voltmeter

A high-resistance meter connected in parallel across a voltage source or load to measure potential difference.

Ammeter

A low-resistance meter connected in series within a circuit path to measure electrical current flow.

Clamp-On Ammeter

An ammeter using a transformer jaw mechanism to measure current via magnetic flux without opening or disconnecting the circuit.

Ohmmeter

A meter used to measure electrical resistance across an isolated component in a de-energized circuit using an internal power source.

Megohmmeter (Megger)

A high-voltage testing meter used to measure extremely high resistance and evaluate insulation breakdown in electrical conductors and motor windings.

Kilowatt Hour Meter

An electrical meter driven by a small induction motor that measures and registers total energy consumption over time.

Demand Meter

An electrical meter featuring a peak indicator pointer that records the maximum power usage reached during a billing period.