STEM OnLine Mini Dictionary

An essential mini-dictionary for STEM minds. A list of selected terms from science, technology, engineering, and mathematics, with clear, straightforward, and engaging definitions right at your fingertips.

Antinode

Point of a standing wave where the amplitude of oscillation reaches its maximum value.

Apoapsis

Point in an orbit where the celestial body is at its maximum distance from its center.

Apogee

Point in the lunar orbit where the Moon is farthest from the Earth.

Apothem

The perpendicular distance from the center of a regular polygon to the midpoint of any of its sides.

Apparent Depth

Visual effect caused by refraction where a submerged object appears to be closer to the surface than it actually is.

Apparent Motion of the Sun

Sun’s movement in the sky as seen from Earth due to Earth’s rotation and orbit.

Apparent Weight

Net force acting on a submerged body, resulting from the difference between its real weight and the buoyant force (Pa = P – E) in the SI.

Applied Force

External force directly exerted on an object to modify its physical or motion state.

Archimedes’ Principle

Law stating that any body immersed in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid.

Area

Magnitude that measures the extent of a two-dimensional surface; its standard SI unit is the square meter (m²) and in the imperial system the square foot (ft²).

Area Calculation

Mathematical process to determine the measurement of a surface using geometric formulas or integration.

Arithmetic Mean

The average value of a set of numerical data, calculated as the quotient of the sum of all values and the total number of data points.

Asteroid Belt

Region between Mars and Jupiter containing most of the system’s asteroids.

Astronomical Unit

Unit of distance equivalent to the average separation between Earth and the Sun.

Astrophysics

Branch of physics studying celestial bodies and phenomena in the universe.

Atmosphere

The gaseous layer surrounding the Earth, held by gravity, which protects life by absorbing ultraviolet radiation and regulating temperature.

Atmospheric Composition

Mixture of gases that make up the air, primarily composed of Nitrogen (78%) and Oxygen (21%).

Atmospheric Corrosion

Spontaneous deterioration of a metal by the formation of an accidental galvanic cell with oxidizing agents from the environment.

Atmospheric Humidity

Amount of water vapor present in the air, originating from the evaporation of water bodies and biological transpiration.

Atmospheric Pressure

Force exerted by air on the Earth’s surface; its common units of measurement are the millibar (mbar), millimeter of mercury (mmHg), pascal (Pa), or atmosphere (atm).

Atom

Basic unit of ordinary matter composed of a dense nucleus surrounded by a cloud of electrons.

Atom-Light Interaction

Physical process through which an atom’s electrons absorb or emit radiant energy in the form of photons.

Atomic Mass Unit

One-twelfth of the mass of a carbon-12 (¹²C) atom, used to express masses of atoms and molecules.

Atomic Nucleus

Central region of the atom, positively charged, containing almost all the mass of the system as protons and neutrons.

Atomic Number

Total number of protons in each atom of a given chemical element, represented by the letter Z.

Aurora

Luminous phenomenon in the atmosphere caused by the interaction of solar particles with the magnetic field.

Avogadro’s Law

States that equal volumes of different gases, at the same pressure and temperature, contain the same number of molecules.

Axiom

Statement or fundamental principle accepted without proof, forming the basis of a mathematical system.

Back Electromotive Force

Voltage induced in a coil that opposes the source voltage, following Lenz’s law.

Ballistic Pendulum

System designed to determine the velocity of a projectile by measuring the height it reaches after impact.

Barometer

Instrument used to measure atmospheric pressure, essential for predicting changes in the weather.

Base

Substance that has a pH higher than 7 and can accept hydrogen ions or release hydroxyl ions.

Basic Salt

Salt containing hydroxyl groups (OH⁻) in its structure due to incomplete neutralization of the base.

Beaufort Scale

Empirical system classifying wind intensity based on its effects.

Bernoulli’s Equation

Energy conservation law for ideal fluids relating pressure, velocity, and height (P + 1/2 * ρ * v² + ρ * g * h = const).

Beta Emission (β)

Nuclear process where a neutron transforms into a proton by emitting a high-energy electron or positron.

Calculus

Branch of mathematics analyzing change using derivatives, integrals, and limits to solve continuous problems.

Calorie

Amount of energy required to raise the temperature of one gram of pure water by 1 °C. It is equivalent to 4.184 J.

Capacitance

Ability of a component to store electric charge per unit of potential difference, defined as C = Q / V and measured in Farads (F) in the SI.

Capacitor

Passive component designed to store electrical energy in the form of an electrostatic field between two conductive plates.

Capacitor Charging

Dynamic process in which a capacitor accumulates energy, its voltage increasing exponentially until it equals that of the source.

Capacitor Discharging

Dynamic process in which a capacitor releases stored energy through a resistor, its voltage decreasing exponentially to zero.

Carbon Dioxide

Main greenhouse gas generated by burning fossil fuels and respiration.

Cartesian Plane

A two-dimensional system formed by two perpendicular graduated lines that allow any point to be located using a pair of coordinates $(x, y)$.

Catalyst

Substance that increases the rate of a chemical reaction without being consumed or permanently altered in the process.

Catalytic Electrode

Conductive surface that facilitates the redox reaction of external gases without being consumed or degraded during the process.

Cathetus

Each of the two sides that form the right angle in a right triangle.

Cation

Ion with a positive electrical charge formed when a neutral atom loses one or more electrons.

Celestial Equator

Great circle on the celestial sphere resulting from projecting Earth’s equator into space.

Celestial Meridian

Great circle passing through the celestial poles and an observer’s zenith.

Celestial Pole

Intersection points of Earth’s rotation axis with the celestial sphere.

Celestial Sphere

Imaginary sphere of infinite radius, centered on the Earth, onto which celestial bodies are projected.

Center of Buoyancy

Point where the buoyant force is considered to be applied, coinciding with the center of gravity of the displaced fluid volume.

Center of Gravity

Specific point where the resultant gravitational force of a body is considered to act.

Center of Mass

Geometric point where the entire mass of a system is considered concentrated for motion analysis.

Centrifugal Force

Apparent force that tends to move a body away from the center of rotation when observed from an accelerated system.

Centripetal Acceleration

Quantity that measures the change in velocity direction of a body following a curved path.

Centripetal Force

Net force directed toward the center of the trajectory that forces a body to follow a curve.

Chain Reaction

Fission process where released neutrons strike other heavy nuclei, causing a series of successive and self-sustained fissions.

Change in Momentum

Change experienced in a body’s momentum, which is numerically equal to the received impulse.

Charles’s Law

States that, at constant pressure, the volume of a gas is directly proportional to its absolute temperature (V₁/T₁ = V₂/T₂).

Chemical Bond

Set of forces that hold atoms, ions, or molecules together to form more complex and stable structures.

Chemical Compound

Substance formed by the chemical union of two or more elements in defined proportions.

Chemical Element

Pure substance formed by atoms with the same number of protons.

Chemical Energy

Potential energy stored in chemical bonds that is released or absorbed during a reaction.

Chemical Equation

Symbolic representation of a chemical reaction showing the substances that react and those that are produced.

Chemical Law

General relationship experimentally verified that describes the behavior of chemical substances.

Chemical Model

Simplified representation of chemical substances or processes allowing study and prediction.

Chemical Property

Characteristic of a substance describing its behavior during a chemical transformation.

Chemical Quantity

Measurable property of a chemical system expressed using a numerical value and a unit.

Chemical Reaction

Thermodynamic process in which one or more substances transform their molecular structure and bonds to form new substances.

Chromatic Aberration

Optical defect common in refractors where colors do not focus at the same point, creating colored edges.

Dalton’s Law

States that the total pressure of a gas mixture is equal to the sum of the partial pressures of each individual gas.

Damping

Energy dissipation process in an oscillatory system that gradually reduces the amplitude of motion.

Data Distribution

The way the values of a variable are organized and spread, allowing for the identification of patterns and trends.

Declination

Celestial coordinate equivalent to latitude, measured north or south of the celestial equator.

Decomposition Potential

Minimum external voltage that must be applied to an electrolytic cell for electrolysis to occur continuously.

Decomposition Reaction

Process in which a single compound fragments into two or more simpler substances.

Definition

Precise explanation of the meaning of a concept within a formal system.

Deformation

Change in the length or shape of an elastic body (stretching or compression) relative to its equilibrium position.

Degree

Angular measurement unit that divides a circle into 360 equal parts (°).

Degree Celsius

Temperature unit based on the freezing (0 °C) and boiling (100 °C) points of water at standard pressure.

Degree Fahrenheit

Temperature scale where the freezing point of water is 32 °F and the boiling point is 212 °F.

Denominator

The lower number that determines how many equal parts the unit is divided into; it can never be zero due to mathematical impossibility.

Density

Scalar quantity expressing the amount of mass per unit volume of a substance, measured in kg/m³ in the SI.

Dependent Variable

A magnitude whose value is determined by the function’s correspondence rule when applied to the independent variable.

Derivative

A function that measures the rate of change of one variable with respect to another, mathematically representing the slope of the curve at each point.

Destructive Interference

Phenomenon that occurs when waves meet in phase opposition, subtracting their amplitudes and potentially canceling each other out.

Deuterium

Stable isotope of hydrogen containing one proton and one neutron in its nucleus.

Dew Point

Specific temperature to which an air mass must be cooled to reach saturation and begin condensation.

Diagonal

A line segment connecting two non-consecutive vertices of a polygon.

Diatomic Gas

Molecule formed by two atoms of the same element, as occurs with elemental hydrogen in nature.

Dielectric

Insulating material that, when placed between the plates of a capacitor, increases its capacitance by reducing the internal electric field.

Dielectric Strength

Maximum electric field intensity that an insulator can withstand before becoming conductive (breakdown).

Differentiability

A property of a function that guarantees the existence of its derivative at a given point or interval.

Diffuse Reflection

Scattering of light in multiple directions when striking a rough surface, preventing the formation of sharp images.

Diffusion

Process by which the particles of one gas gradually mix with those of another due to their random thermal motion.

Digital Circuit

Electrical circuit operating with discrete signals represented by defined levels.

Dilution

Procedure that consists of decreasing the concentration of a solute by adding more solvent.

Diminished Image

Type of image produced by diverging lenses that is always smaller in size than the actual object.

Direct Current

Type of electric current in which charges move always in the same direction.

Direct Proportion

A relationship where an increase in one magnitude causes a proportional increase in the other, keeping their quotient constant.

Direct Proportionality

Relationship in a voltage divider where a higher resistance corresponds to a higher voltage drop (V ∝ R).

Direction

The straight line upon which the vector lies, defined by the angle it forms with the reference axes.

Displaced Volume

Space occupied by the fluid that has been moved aside by the body upon immersion, measured in m³ in the SI.

Displacement

Vector quantity that measures the change in position of an object from its initial point to its final point.

Dissipated Power

Part of the electrical power that is lost in the form of heat due to the resistance of components or conductors.

Dissipative Force

Force that transforms work into non-recoverable energy, usually heat (such as friction), depending on the path.

Earth

Third planet from the Solar System, the only one with confirmed life and surface liquid water.

Earth Model

Simplified representation of the Earth system for study and prediction.

Earth System

Set formed by the lithosphere, hydrosphere, atmosphere, and biosphere interacting.

Earth’s Crust

Outermost and thinnest layer of the Earth, composed of solid rocks.

Earth’s Magnetic Field

Magnetic field surrounding the Earth, originated by the movement of liquid metals in its core, acting as a protective shield.

Earthquake

Sudden release of energy in the Earth’s crust in the form of seismic waves, caused by the movement of faults or tectonic plates.

Eccentricity

Measure of how much a planet’s orbit deviates from being a perfect circle.

Ecliptic

Curved line along which the Sun’s apparent motion occurs as seen from Earth.

Effusion

Process by which a gas under pressure escapes from a container to the outside through a small opening.

Elastic Collision

Collision in which the total kinetic energy of the system is conserved, with no transformation of energy into heat or deformation.

Elastic Energy

Energy stored in bodies when deformed, measured in joules (J) and dependent on the elasticity constant.

Elastic Force

Force exerted by objects such as springs that have been deformed and seek to return to their original shape.

Elastic Limit

Maximum deformation a material can withstand without undergoing permanent changes in its shape.

Elastic Potential Energy

Energy stored in an elastic body when deformed, which is released when it returns to its original shape.

Electric Charge

Intrinsic property of subatomic particles that determines their electromagnetic interaction, measured in Coulombs (C) in the SI.

Electric Circuit

Set of interconnected components forming a closed path through which an electric current can flow.

Electric Energy

Total amount of work performed by the electric current in a given time, calculated as E = P · t and measured in Joules (J) or kWh.

Electric Field

Region of space where a charge experiences a force. It is defined by the relationship F = q · E, where force is the product of the charge and the field intensity.

Electric Field Intensity

Vector quantity that quantifies the force per unit charge (E = F / q), measured in N/C or V/m in the SI.

Electric Generator

Device that converts mechanical energy into electrical energy based on electromagnetic induction by moving a conductor in a magnetic field.

Electric Load

Any circuit component (lamps, motors) that consumes electrical energy to perform work.

Electric Motor

Device that converts electrical energy into mechanical energy through the interaction of magnetic fields and currents.

Electric Power

Rate at which energy is consumed or supplied in a circuit, calculated as P = V · I and measured in Watts (W).

Electrical Component

Individual element of a circuit performing a specific function within the system.

Electrical Conductivity

Measure of a material’s ability to carry electrical current. The SI unit of measurement is the Siemens per meter (S/m).

Electrical Efficiency

Ratio between the useful power used by the load and the total power supplied by the source, expressed as a percentage.

Electrical Energy

Energy derived from the movement of electrons through a conductor due to a potential difference.

Electrical Model

Simplified representation of an electrical circuit or system used for study.

Electrical Quantity

Measurable property of an electrical system expressed using a value and a unit.

Electrical Resistance

Measure of the opposition a material offers to the flow of electric current through it, measured in Ohms (Ω) in the SI.

Electrical Signal

Variation of an electrical quantity that carries information or energy.

Electrical System

Set of circuits and components interacting to perform an electrical function.

Electrochemistry

Discipline studying the reciprocal transformation between chemical and electrical energy through electronic transfer processes.

Electrodeposition

Process in which an electric current reduces metal ions in solution to form a solid coating on an electrode.

Electrolysis

Chemical decomposition phenomenon induced by an external electric current passing through an electrolyte.

Electrolyte

Substance that, when dissolved in water, dissociates into ions and allows the conduction of electric current.

Faraday’s Law

Law stating that the induced electromotive force (EMF) is proportional to the rate of change of magnetic flux: ε = -dΦ / dt.

Ferromagnetic Core

Material (such as iron) placed inside a coil to concentrate field lines and multiply its inductance.

Ferromagnetism

Property of materials like iron that exhibit strong magnetization in the presence of an external magnetic field.

Field Lines

Visual representation of the direction and strength of the electric field; they originate from positive charges and terminate at negative charges.

Final Velocity

Velocity vector possessed by a body at the instant the study interval of its motion is concluded.

Fissionable Isotope

Variety of a chemical element (such as Uranium-235) whose nucleus is capable of undergoing fission after capturing a neutron.

Fixed Pulley

Device with a stationary axle that changes the direction of the force without changing its magnitude.

Flight Time

Total duration an object remains in the air from the start of a jump until it returns to the reference level.

Flow

Continuous movement of a mass of fluid through a space or conduit in a specific direction.

Flow Rate

Volume of fluid passing through a section per unit of time (Q = V / t), measured in m³/s in the SI.

Fluid Mechanics

Branch of physics studying the behavior of liquids and gases in motion.

Focal Length

Path that light travels from the objective to the point where the sharp image is formed.

Focal Point (Focus)

Point where parallel reflected rays converge in a concave mirror (or from which they appear to originate in a convex one).

Focus

One of the two interior fixed points that define the shape of an orbital ellipse.

Focusing

Adjustment of the distance between the lens and the image plane so that the rays converge exactly on a detector surface.

Foehn Wind

Dry and warm wind descending the leeward slope of a mountain.

Force

Interaction capable of modifying the state of rest or motion of a body, or of producing a deformation in it.

Foucault Pendulum

Long-length device used to demonstrate Earth’s rotation through the precession of its oscillation plane.

Fourier Coefficients

Numerical values that determine the amplitude or weight of each sine and cosine in the reconstruction of the original function.

Fourier Series

The representation of a periodic function as an infinite sum of sinusoidal functions (sines and cosines) with different frequencies.

Fourier Synthesis

The process of reconstructing a complex signal by superimposing its individual sinusoidal components.

Fraction

An expression representing the division of a quantity into equal parts, indicating how many of those parts are taken from the total.

Frame of Reference

Set of conventions used by an observer to measure the position and motion of a body.

Free Fall

Particular case of uniformly accelerated motion where the acceleration is gravity and there is no air resistance.

Frequency

Number of complete turns or revolutions an object makes in a given unit of time.

Frequency Domain

Analysis of a function through its spectral components, showing how much energy exists at each frequency.

Friction

Force that opposes the relative motion between two surfaces in contact.

Friction Force

Force opposing motion that arises from the interaction between two surfaces in contact.

Fuel Cell

Type of galvanic cell designed to operate continuously by the external flow of reactants toward the electrodes.

Fulcrum

Physical place on which an object pivots or rests to transmit or multiply a force.

Function

Relation assigning to each element of a set exactly one element of another set.

Fundamental Frequency

The lowest frequency in a Fourier series that defines the basic period of the original function.

Galaxy

Huge collection of stars, gas, and dust bound by gravity.

Galvanic Cell

Electrochemical device that transforms chemical energy into electrical energy through spontaneous electron transfer reactions.

Gamma Radiation (γ)

Emission of high-frequency electromagnetic waves with high penetrating power that often accompanies alpha and beta processes.

Gas

State of aggregation of matter in which particles have minimum attraction to each other and occupy the entire volume of the container.

Low Tide

The moment when sea water reaches its minimum height within the tidal cycle.

Lubrication

Application of substances to reduce friction and wear between contacting surfaces.

Luminosity

Measure of the total power output of a star or other astronomical object.

Lunar Eclipse

Event where the Earth comes between the Sun and the Moon, casting its shadow on it.

Lunar Phases

Apparent changes in the visible illuminated portion of the Moon from Earth.

Magnetic Declination

Angle between true north and the north indicated by a compass.

Magnetic Dipole

System composed of two opposite poles (north and south); isolated magnetic poles (monopoles) do not exist in nature.

Magnetic Energy

Energy accumulated within the magnetic field generated by the inductor during the passage of electric current.

Magnetic Field

Region of space where a moving electric charge experiences a magnetic force, measured in Teslas (T) in the SI.

Magnetic Flux

Measure of the amount of magnetism passing through a surface, calculated as Φ = B · A · cos(θ) and measured in Webers (Wb) in the SI.

Magnetic Permeability

Ability of a material to allow magnetic field lines to pass through it, measured in H/m in the SI.

Magnetic Pole

Point on the Earth’s surface where the magnetic field lines are vertical.

Magnetic Reversal

Event in which the Earth’s magnetic north and south poles swap positions.

Magnetosphere

Region around the Earth dominated by its magnetic field that deflects solar wind.

Magnification

Ratio between the size of the formed image and the actual size of the object observed through the lens.

Magnifying Glass

Optical instrument consisting of a short-focal-length convex lens that produces a virtual, upright, and enlarged image.

Magnitude

Any physical or mathematical property that can be measured or counted and expressed through a numerical value.

Mantle

Intermediate layer of the Earth located between the crust and the core.

Mars

Fourth planet, called the Red Planet due to the iron oxide on its surface.

Mass

Amount of matter in a body, constant throughout the universe. The SI unit of measurement is the kilogram (kg) and in the English system the pound (lb).

Mass Number

Sum of the number of protons and neutrons present in the nucleus of an atom, represented by the letter A.

Mass-Energy Equivalence

Physical principle stating that the energy released in a nuclear reaction comes from a small loss of mass during the process.

Materials Chemistry

Branch of chemistry studying structure, properties, and applications of solid and functional materials.

Mathematical Equality

A proposition of equivalence between two expressions separated by the = sign, indicating they both represent the same logical value.

Mathematical Function

A dependency relationship between two magnitudes where each input value corresponds to exactly one output value.

Mathematical Ratio

A binary link between two magnitudes expressed as a quotient to determine how many times one contains the other.

Maximum Kinetic Energy

Excess energy possessed by the electron after being released, which depends solely on the frequency of the incident light.

Measurement Resolution

The smallest variation in the measured quantity that the instrument is capable of detecting and displaying on its screen.

Measuring Instrument

Device used to measure electrical quantities within a circuit.

Mechanical Advantage

Numerical ratio indicating how much the applied force is multiplied in a simple machine relative to the resistance.

Mechanical Energy

Sum of the kinetic energy and potential energy of a body or system in a given state.

Mechanical Wave

Type of wave that strictly requires a material medium (solid, liquid, or gas) in order to propagate.

Mechanical Work

Scalar quantity resulting from force by displacement and the cosine of the angle between them, measured in joules (J).

Median

The central value of an ordered data set that divides the sample into two equal parts, with 50% of the data above and 50% below.

Melting point

Temperature at which a substance changes from solid to liquid state at a given pressure.

Member

Each of the two expressions located on either side of the equal sign; called the first and second members.

Membrane Electrolyte

Selective barrier that allows the passage of specific ions between electrodes while blocking the direct passage of electrons and gases.

Mercalli Scale

Qualitative scale that measures seismic intensity based on observed effects and damage to people and structures.

Mesh (Loop)

Any closed path in a circuit that does not contain other closed paths within it.

Mesh Equation

Mathematical expression resulting from applying the voltage law to a closed path to find unknown currents.

Mesosphere

Middle layer of the atmosphere where temperature reaches its lowest levels and most meteoroids disintegrate.

Paraffin

Technical name for alkanes highlighting their low reactivity towards most chemical reagents.

Parallel Circuit

Configuration where components are connected to the same nodes, sharing the same voltage but splitting the current.

Parallel Inductors

Configuration where inductor terminals are connected to common points, decreasing the total equivalent inductance of the circuit.

Parallel Measurement

Connection method of an instrument (such as a voltmeter) where it is placed between the two points whose potential difference is to be known.

Parallel Plate Capacitor

Device consisting of two parallel conductors separated by an insulator, whose capacitance is calculated as C = ε · A / d.

Partial Pressure

Pressure that an individual gas in a mixture would exert if it alone occupied the entire volume of the container at the same temperature.

Partial Voltage Drop

Decrease in electric potential in a specific section of the mixed circuit, depending on the local configuration of that section.

Pascal’s Principle

Law stating that pressure exerted at any point in a fluid is transmitted with equal intensity in all directions.

Passive Elements

Components that consume or store electrical energy without generating power gain, such as resistors, capacitors, and coils.

Path Difference

Extra distance one wave travels relative to another to reach the same point, defined by the relationship Δx = x2 – x1.

Pendulum Length

Distance measured from the suspension point to the center of mass of the oscillating body.

Penumbra

Region of partial shadow surrounding the umbra during an eclipse.

Perfectly Inelastic Collision

Case where bodies remain joined after impact, resulting in the maximum possible loss of kinetic energy.

Periapsis

Point in an orbit where the celestial body is at its minimum distance from its center.

Perigee

Point in the lunar orbit where the Moon is closest to the Earth.

Perimeter

The total length of a polygon’s boundary, obtained by summing the measures of all its sides.

Period

Time required for an object in circular motion to complete one full revolution or turn.

Periodic Function

A function that repeats its values at regular intervals of time or space, called periods.

Permafrost

A layer of soil or rock that remains continuously frozen for at least two consecutive years.

Permittivity

Property of a material or vacuum that describes how much it allows or opposes the formation of an electric field within it.

pH

Logarithmic measure indicating the concentration of hydrogen ions in a solution. Its scale typically ranges from 0 (very acidic) to 14 (very basic).

pH Indicator

Chemical substance that changes color depending on the acidity or basicity level of the solution it is in.

pH Meter

Precision electronic instrument used in the laboratory to measure the pH value of a solution using an electrode.

pH Scale

Numerical range used to specify the acidity or basicity of an aqueous solution.

Phase

State of vibration of a particle at a given instant, defined by the angle that determines its position and direction of motion.

Phase Angle

Time or angular difference between the voltage and current peaks in an alternating current circuit.

Phase Difference

Measure of the relative separation in the cycle of two waves at a given point, usually expressed in radians.

Phase Shift

Angle indicating how much a wave is leading or lagging relative to another at a specific instant.

Photocurrent

Flow of electrons released by the photoelectric effect that generates a measurable electric current in a circuit.

Photoelectric Cell

Electronic device that uses the photoelectric effect to convert light energy directly into electrical energy.

Photoelectric Effect

Emission of electrons from a material when exposed to electromagnetic radiation of sufficiently high frequency.

Photon

Quantum of electromagnetic radiation representing the minimum unit of interaction between light and electrons.

Photosphere

Luminous surface of the Sun that emits most of the radiation we receive.

Physical Chemistry

Branch of chemistry studying physical principles that explain the behavior of chemical systems.

Physical Law

Proposition describing a universal behavior in nature based on repeated observations.

Physical Model

Simplified representation of a physical system allowing its study and prediction.

Quadrant

Each of the four regions into which the axes divide the Cartesian plane, numbered I to IV in a counterclockwise direction.

Quantization

Phenomenon by which physical quantities such as energy cannot vary continuously, but in discrete steps or packets”.”

Quantum Algorithm

Sequence of logical operations executed on a quantum computer to perform specific tasks with superior efficiency.

Quantum Computing

Computing paradigm that leverages phenomena such as superposition and entanglement to solve problems unreachable for classical computers.

Quantum Cryptography

Secure communication method that uses the laws of quantum physics to detect any attempt at data interception.

Quantum Decoherence

Process by which a quantum system loses its superposition properties due to interaction with the environment, becoming classical”.”

Quantum Entanglement

Intimate connection between particles where the state of one instantaneously depends on the state of the other, regardless of the distance separating them.

Quantum Mechanics

Branch of physics describing the behavior of matter and energy at atomic scales, where the laws of classical physics are no longer valid.

Quantum Probability

Measure of the possibility of a system being in a certain state after a measurement is performed, replacing classical certainty.

Quantum State

Physical condition describing all measurable properties of a system at the subatomic level at a given moment.

Quantum Supremacy

Point at which a quantum computing device can perform a calculation that is practically impossible for the most powerful classical supercomputer.

Quantum Teleportation

Process of transferring quantum state information to a remote location using entanglement and classical communication.

Qubit (Quantum Bit)

Basic unit of quantum information that, thanks to superposition, can represent 0, 1, or both states simultaneously.

Radial Velocity

Component of an object’s velocity that moves directly away from or toward the observer.

Radian

Angle measurement unit in the SI representing the central angle whose arc length is equal to the radius; it is approximately equal to 57.29°.

Radiant Energy

Energy transmitted through electromagnetic waves that can propagate through a vacuum.

Radiative Forcing

Change in the atmosphere’s net energy flow caused by climate factors.

Radio Telescope

Specialized antenna that captures radio waves from astronomical sources in space.

Radioactivity

Spontaneous process of decay of unstable atomic nuclei through the emission of particles and electromagnetic energy.

Radius of Curvatura

Design parameter defining the shape of the lens surface and determining its ability to converge or diverge light.

Radius of Rotation

Constant distance between the center of the circular path and the position of the moving particle.

Random Experiment

A process or action whose exact outcome cannot be predicted with certainty before it occurs, even under the same initial conditions.

Range or Image

The subset of values in the codomain that are actually reached by the function when the full domain is applied.

RC Circuit

Electrical configuration consisting of a resistor and a capacitor that exhibits time-dependent dynamic behavior.

Reactance

Opposition to the flow of alternating current due to inductance or capacitance, causing a phase shift between voltage and intensity.

Reactant

Initial substance that participates in a chemical reaction and is consumed to form new products.

Real Focal Point

Point where light rays physically converge after passing through a convex lens, allowing images to be projected.

Real Gas

Gas that does not behave exactly according to ideal laws due to intermolecular interactions and the actual volume of its particles.

Real Image

Image formed by the actual convergence of reflected rays, which can be projected onto a surface.

Real Numbers

The set comprising all rational and irrational numbers, allowing for the infinite continuity of the number line.

Reciprocal

The result of transposing the terms of a fraction; multiplying it by the original fraction always results in the number one.

Redshift

Phenomenon where an object’s light shifts toward longer wavelengths because it is moving away from the observer.

Reflected Ray

Light beam that moves away from the surface after bouncing off the point of incidence.

Reflecting Telescope

Instrument that uses curved mirrors instead of lenses to collect and focus light.

Reflexive Property

An axiom stating that every quantity is equal to itself (a = a), a fundamental basis of identity.

Refracted Ray

Light beam that, after passing through the separation surface between two media, continues its propagation in a different direction.

Salt

Chemical compound formed by cations and anions through an ionic bond, typical result of the reaction between an acid and a base.

Salt Hydrolysis

Reaction of the ions of a dissolved salt with water, which can alter the pH of the solution.

Sample

A representative subset selected from a population upon which statistical observations and measurements are performed.

Sample Space

The set of all possible outcomes that can result from a given random experiment.

Satellite

Body orbiting a planet, natural or artificial.

Saturated Air

State in which the air contains the maximum possible amount of water vapor for a given temperature (100% relative humidity).

Saturated Hydrocarbon

Organic compound containing the maximum possible number of hydrogen atoms per carbon, with no double or triple bonds.

Saturation

State of a solution containing the maximum amount of solute that the solvent can hold at a given temperature.

Saturn

Gas giant famous for its extensive and bright ring system.

Scale

A constant proportion of measurement that establishes the unit distance between numbers, ensuring a coherent graphic representation.

Scatter Plot

A two-dimensional graphical representation of data where each point represents the value of two variables, allowing visual identification of their correlation.

Sea Breeze

Local wind blowing from the sea toward the land during the day.

Secant Line

A line that intersects a curve at two points; its slope represents the average rate of change between those two values.

Seism

A synonym for earthquake, commonly used in technical contexts to refer to any vibratory movement of the earth.

Seismic Wave

Elastic wave that propagates the energy of an earthquake; its propagation speed is measured in kilometers per second (km/s).

Seismograph

Precision instrument used to detect, measure, and record Earth’s vibrations.

Self-Induction

Phenomenon by which a changing current in a coil induces an electromotive force within itself to oppose the change in flux.

Semi-major Axis

Half of the longest diameter of an ellipse, used to define the size of an orbit.

Semiconductor

Material whose ability to conduct electricity is intermediate and can be controlled under certain conditions.

Sense

The orientation of the vector’s arrow, indicating towards which end of the direction it is headed.

Series Circuit

Configuration where components are connected one after another, so that the same current flows through all of them.

Series Inductors

Configuration where coils are connected one after another, directly adding their values to obtain a higher equivalent inductance.

Series Measurement

Connection method of an instrument (such as an ammeter) where the current must mandatorily pass through the equipment.

Short Circuit

Path of virtually zero resistance joining two points of different potential, causing a dangerous increase in current.

Short-Circuit Current

Maximum current delivered by the original circuit when its two output terminals are directly connected to each other with zero resistance.

Simple Harmonic Motion

Periodic back-and-forth motion in which a body oscillates about an equilibrium position under the action of a restoring force.

Simple Pendulum

Idealized model consisting of a point mass suspended from an inextensible, weightless string.

Simplification

The technique of reducing a fraction to its lowest terms by dividing both the numerator and denominator by a common divisor.

Sine

Trigonometric ratio defined as the quotient between the side opposite an angle and the hypotenuse.

Sinusoidal Waves

Smooth mathematical functions describing repetitive oscillations, fundamental for signal analysis.

Sliding

Relative motion between two surfaces in contact without rolling.

Slope

A measure of the inclination of a line relative to the horizontal axis, calculated as the ratio of vertical change to horizontal change.

Slope of the Curve

A numerical value indicating the steepness of the tangent line to the function at a specific point in the domain.

Snell’s Law

Principle relating the refractive indices of two media to the angles of incidence and refraction of light.

Solar Corona

Outermost layer of the Sun’s atmosphere, made of plasma and visible during total eclipses.

Solar Declination

Angle between the Sun’s rays and the plane of the Earth’s equator.

Vector Component

Projection of a vector quantity onto the axes of a coordinate system to analyze its effects independently.

Vector Components

Projections of a vector onto the axes of the Cartesian coordinate system.

Vector Magnitude

The length or size of the vector, calculated as the square root of the sum of its squared components.

Velocity Variation

Difference between the final velocity and the initial velocity of a body during a time interval.

Velocity-Time Graph

Visual representation where the slope of the straight line indicates the value of the movement’s acceleration.

Venus

Second planet in the Solar System, known for its dense carbon dioxide atmosphere and high temperatures.

Vertex

The joining point where two sides of a polygon meet and where the angle is formed.

Vertical Displacement

Change in position of an object measured along the axis perpendicular to the horizon.

Vertical Rectilinear Trajectory

Path followed by an object in ascent or descent perpendicular to the ground following the direction of gravity.

Virtual Focal Point

Point from which light rays appear to originate after being scattered by a concave lens.

Virtual Image

Image formed by the extension of reflected rays that appears to be located behind the mirror.

Voltage (Tension)

Electric potential difference between two points in a circuit that drives the movement of charges, measured in Volts (V).

Voltage Divider

Configuration of resistors in series that distributes the total source voltage proportionally to each resistor.

Voltage Drop

Decrease in electric potential when passing through a resistive component due to the energy consumption of the charges.

Voltmeter

Instrument used to measure the potential difference between two points; it is always connected in parallel.

Water

Inorganic compound formed by two hydrogen atoms and one oxygen atom (H₂O), essential for all known life forms.

Water Vapor

Water in a gaseous state that mixes with the air; it is the main driver of cloud formation and meteorological phenomena.

Watt

Unit of power representing the transfer or consumption of one joule of energy per every second of time.

Wave

Perturbation that propagates carrying energy without net transfer of matter, measured in joules (J) for the energy carried.

Wave amplitude

Maximum displacement of the perturbation from its equilibrium position or central value.

Wave Function (Ψ)

Mathematical entity containing probabilistic information about the position and state of a quantum particle.

Wave Reflection

Change in direction of a pulse upon reaching the end of the string, potentially inverting its phase depending on whether the end is fixed or free.

Wave-Particle Duality

Fundamental concept stating that light exhibits properties of both electromagnetic waves and discrete particles.

Wavelength

Physical distance between two consecutive points that are in the same state of vibration, measured in meters (m).

Weight

Gravitational force acting on a mass and varies by location. The SI unit of measurement is the Newton (N) and in the technical system the kilopond (kp).