STEM OnLine Mini Dictionary
Ablation
The total loss of ice and snow from a glacier due to melting, evaporation, or the calving of icebergs.
Abscissa Axis
The horizontal line in the Cartesian plane, generally represented by the variable $x$.
Absolute Frequency
The number of times a specific value or response occurs within a data set.
Absolute Value
The numerical magnitude of a value regardless of its sign, defined as the positive distance between that number and the origin.
Absolute Zero
Theoretical minimum temperature (0 K or -273.15 °C) at which particles reach their minimum energy level.
Absorbed Power
Total power consumed by a receiver or component to perform its function and cover its internal losses.
Acceleration
Change in the velocity vector of a body per unit of time as a result of a net force.
Acid
Substance that has a pH lower than 7 and is capable of releasing hydrogen ions in a solution.
Acid Salt
Salt containing replaceable hydrogen atoms in its structure, coming from a partially neutralized polyprotic acid.
Activation Energy
Minimum amount of energy required for a chemical reaction to start. It is usually measured in joules per mole (J/mol).
Active Elements
Circuit components capable of supplying electrical energy or controlling current flow, such as power supplies.
Additive Synthesis
Method of obtaining colors by adding lights of different wavelengths, used in screens and RGB systems.
Air Resistance
Friction force exerted by the atmosphere that opposes the motion of a falling body.
Albedo
Proportion of sunlight that a planetary surface reflects back into space.
Algebra
Branch studying structures and operations using symbols and formal rules.
Algebraic Equality
An expression including numbers and letters (variables), which can be true for certain values or for all of them.
Alkane
Hydrocarbon composed only of carbon and hydrogen atoms joined by single bonds.
Alkyl Group
Structure resulting from removing a hydrogen atom from an alkane, allowing it to attach to a main chain as a branch.
Alpha Emission (α)
Type of decay where the nucleus emits a heavy particle composed of two protons and two neutrons (Helium-4 nucleus).
Alternating Current
Type of electric current in which charges periodically change direction.
Altitude
Vertical distance of a point relative to sea level (m); it is the main factor determining pressure variation.
Ammeter
Instrument designed to measure current intensity; it must always be connected in series within the circuit.
Amphoterism
Chemical ability of water to act as an acid or a base depending on the substance it reacts with.
Amplitude
Maximum displacement value of an oscillating body relative to its equilibrium position.
Analemma
Figure-eight curve representing the Sun’s position if observed daily at the same time.
Analytical Chemistry
Branch of chemistry studying methods to identify and quantify chemical substances.
Anemometer
Instrument used to measure wind speed.
Angle
The opening formed by two rays with a common origin called a vertex; its standard SI unit is the radian (rad), though it is commonly measured in degrees (°).
Angle of Incidence
Angle formed between the incident ray and the normal line at the point of contact with the surface.
Angle of Refraction
Angle between the normal line and the light ray propagating through the second medium.
Angular Displacement
Angle swept by an object in circular motion, generally measured in radians.
Angular Frequency
Measure of the rotation rate or the rate of change of the motion’s phase, expressed in radians per second (rad/s).
Angular Velocity
Rate at which an object’s angular displacement changes per unit of time.
Anion
Ion with a negative electrical charge formed when a neutral atom gains one or more electrons.
Antecedent
The first term of a ratio (numerator) that is compared with the second to establish a quantitative relationship.
Anticyclonic Wind
Air rotating outward from a high-pressure center.
Continuity
Presence of a complete path for current flow; if one component fails in series, continuity is lost throughout the circuit.
Continuous Spectrum
Uninterrupted distribution of all visible light wavelengths, whose natural decomposition is observed in the rainbow.
Control Elements
Devices that allow governing the passage of electric current, such as switches, push-buttons, or commutators.
Conventional Battery
Device that stores its reactants internally and ceases to supply current when chemical equilibrium is reached.
Converging Lens
Optical device that refracts parallel light rays toward a single common point called the focus.
Convex Lens
Lens that possesses an outward-curved surface and is thicker at its center than at its edges.
Convex Mirror
Spherical mirror with the surface curved outward that diverges light rays and widens the field of view.
Core
Center of the Earth, made of iron and nickel, divided into outer and inner.
Coriolis Effect
Deflection of the wind’s path due to the Earth’s rotation.
Correlation Coefficient (r)
A numerical index that quantifies the degree of linear association between two variables, ranging from -1 to +1.
Correspondence Rule
An algebraic expression or algorithm that defines exactly how to transform a domain value into a codomain value.
Cosine
Trigonometric ratio defined as the quotient between the side adjacent to an angle and the hypotenuse.
Cosmic Microwave Background
Residual radiation from the Big Bang that fills the entire universe almost uniformly.
Coulomb’s Constant
Proportionality constant (k) depending on the medium; in a vacuum, its value is approximately 8.99 · 10⁹ N · m²/C² in the SI.
Coulomb’s Law
Law stating that the force between two charges is proportional to the product of their charges and inversely proportional to the square of the distance: F = k · (q1 · q2) / r².
Couple of Forces
System formed by two equal, parallel, and opposite forces that produce exclusively a rotation.
Covalent Bond
Chemical bond where two atoms share one or more pairs of electrons to achieve a stable electronic configuration.
Critical Angle
Limiting angle of incidence above which light no longer refracts but reflects totally within the medium.
Critical Point
Conditions of pressure and temperature above which the liquid and gaseous phases of a substance are indistinguishable.
Cross Product
An operation that generates a third vector perpendicular to the plane formed by the two original vectors.
Cryosphere
Part of the Earth system that contains water in a solid state, including glaciers, sea ice, and snow.
Crystal Lattice
Highly ordered three-dimensional structure in which the ions of a salt are organized in a solid state.
Current Decay
Dynamic process in which the current decreases exponentially as the inductor releases stored energy.
Current Divider
Configuration of parallel branches that distributes the total source current inversely proportional to the resistance of each branch.
Current Growth
Dynamic process in which the current increases exponentially from zero to the maximum value set by the resistance.
Current Intensity
Amount of electric charge passing through a cross-section of the conductor per unit of time, measured in Amperes (A).
Curve Fitting
A mathematical modeling process that finds the function that best describes the general trend of a set of experimental data.
Cycloidal Pendulum
Type of pendulum whose period is exactly independent of amplitude thanks to its trajectory following a cycloid curve.
Cyclonic Wind
Air rotating inward toward a low-pressure center.
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.
Gas Density
Ratio between the mass of a gas and the volume it occupies. It is usually expressed in grams per liter (g/L).
Gas Properties
Physical and mechanical characteristics that define the behavior of matter in a gaseous state due to low molecular interaction.
Gay-Lussac’s Law
States that, at constant volume, the pressure of a gas is directly proportional to its absolute temperature (P₁/T₁ = P₂/T₂).
General Atmospheric Circulation
Global system of air movements that redistributes heat across the planet.
General Relativity
Theory describing gravity as a curvature of space-time caused by the presence of mass and energy.
Geocentric Model
Ancient theory that placed the Earth at the center of the universe with celestial bodies revolving around it.
Geodesic
Shortest possible path between two points in a curved space, which is the path followed by objects in free fall.
Geodynamo
Physical mechanism explaining how the movement of liquid iron in the core generates the magnetic field.
Geoid
Theoretical shape of the Earth equivalent to the mean sea level extended through the continents.
Geological Fault
A fracture or zone of fracture between two blocks of rock that allows relative displacement between them, accumulating stress released in seisms.
Geological Law
General principle describing observable behaviors and relationships on Earth.
Geological quantity
A measurable property of a geological phenomenon or body, expressed in terms of a value and a unit.
Geological Scale
Temporal classification organizing Earth’s history into geological time units.
Geometric Formula
Mathematical expression that establishes the relationship between a figure’s dimensions to determine its area.
Geometric Optics
Branch of optics that studies light propagation using light rays and geometric representations of reflection and refraction.
Geometric Transformation
An operation that modifies the position, size, or shape of a graph (such as translations or rotations).
Geometry
Studies properties and relations of points, lines, surfaces, and solids in space.
Geostationary Orbit
Circular orbit above the Earth’s equator in which the satellite appears to be fixed in the sky.
Gibbs Phenomenon
An oscillation or overshoot” that occurs in the reconstruction of discontinuous functions (like square waves) near jump points.”
Glacial Cirque
An amphitheater-shaped depression located at the head of a glacial valley, where the snow that feeds the glacier accumulates.
Glacial Erosion
Process of wearing down the Earth’s relief caused by the movement of ice and the dragging of rocky materials.
Glacier
A large mass of compressed ice that forms through snow accumulation and flows slowly under its own weight.
Glacier Tongue
The lower part of a glacier that extends down a valley, characterized by the movement of ice and the erosion of the bedrock.
Global Warming
Increase in the Earth’s average temperature due to the rise in greenhouse gases.
Graphic Scale
The proportional relationship between the distances represented in the drawing and the actual magnitudes of the data.
Gravimetry
Method of measuring local gravitational acceleration based on the oscillation period of a pendulum.
Gravitational Acceleration
Intensity of the gravitational field on the surface. The SI unit of measurement is the meter per second squared (m/s2).
Gravitational Attraction
Force of mutual interaction between bodies with mass, responsible for the bulging of oceanic water masses.
Gravitational Field
Area of space in which a mass exerts its attractive influence on others.
Gravitational Lens
Phenomenon where light from a distant object bends as it passes near a large mass, acting as a cosmic magnifying glass.
Gravitational Potential Energy
Energy that depends on an object’s height relative to a reference level and the force of gravity.
Gravitational Redshift
Stretching of the wavelength of light (towards red) as it attempts to escape from an intense gravitational field.
Gravitational Waves
Ripples in the fabric of space-time produced by violent events, such as the collision of black holes.
Gravity
Mutual force of attraction between bodies with mass.
Greenhouse Effect
Natural process where certain gases trap solar heat to maintain a habitable temperature.
Greenhouse Gases
Gaseous components that trap thermal radiation and regulate the planet’s temperature.
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.
Tangent
Trigonometric ratio defined as the quotient between the opposite side and the adjacent side to an angle.
Tangent Line
A straight line that touches a curve at a single given point and whose slope is equal to the derivative of the function at that point.
Telescope
Optical instrument designed to observe distant objects by collecting electromagnetic radiation.
Temperature
Measure of the average kinetic energy of the particles in a system. It is measured in Kelvin (K), degrees Celsius (°C), or Fahrenheit (°F).
Temperature Coefficient
Factor indicating how the resistance of a material changes with temperature, generally increasing in metals.
Tensile Force
Force transmitted through a stretched flexible object, such as a rope, cable, or chain, pulling on objects at its ends.
Tension
Force exerted by a rope or cable that acts as the physical cause of centripetal acceleration.
Term
Each of the parts separated by addition or subtraction signs within the members of an equality.
Terminal Velocity
Constant maximum speed reached by a falling object when air resistance balances its weight.
Test Lead (Probe)
Insulated metal connectors that allow physical contact to be established between the measuring equipment and the circuit points.
The Moon
Earth’s only natural satellite that influences tides and stabilizes the Earth’s axis.
Theorem
Mathematical proposition provable from axioms and definitions within a logical system.
Thermal Balance
Equilibrium between incoming solar energy and heat energy leaving for space.
Thermal Conductivity
Measure of a substance’s ability to transfer heat through its mass.
Thermal Energy
Internal energy of a system due to the chaotic motion of its particles, manifested as temperature.
Thermal Equilibrium
State in which two bodies in contact reach the same temperature and net heat exchange ceases.
Thermodynamics
Branch of physics studying energy, heat, and the transformations of systems.
Thermosphere
Outer layer of the atmosphere where gas molecules absorb high-energy solar radiation, reaching very high temperatures.
Thévenin Equivalent Circuit
Simplified model that reproduces the same electrical behavior (V, I) as the original network from the load’s perspective.
Thévenin Resistance
Resistance seen from the load terminals when all independent internal sources have been zeroed out (voltage sources short-circuited).
Thévenin Voltage
Open-circuit voltage between the network terminals; it represents the electromotive force of the equivalent model.
Thévenin’s Theorem
Principle that allows replacing any linear network with an equivalent circuit consisting of a single voltage source and a series resistor.
Thin Lens
Transparent optical device whose thickness is negligible compared to the radii of curvature of its surfaces.
Threshold Frequency
Minimum frequency of incident light below which no electron emission occurs, regardless of intensity.
Tidal Current
Horizontal movement of water towards the coast (flood) or towards the sea (ebb) due to the variation in sea level.
Tidal Range
Vertical difference in height between consecutive high and low tides; expressed in meters (m) or feet (ft).
Tide
Periodic change in sea level produced mainly by the gravitational forces exerted by the Moon and the Sun on the Earth.
Time Constant
Temporal parameter calculated as the ratio of inductance to resistance that defines how quickly the current responds to circuit variations.
Time Dilation
Phenomenon where time passes more slowly for an observer moving at high speed compared to one at rest.
Time Domain
The representation of a function or signal based on its evolution over time.
Torricelli’s Experiment
Scientific test that proved air has weight and can support a 760 mm mercury column at sea level.
Torricellian Vacuum
Airless space created at the top of a mercury tube when performing Torricelli’s experiment; it was the first evidence of a man-made vacuum.
Torsion Pendulum
System consisting of a body suspended from an elastic wire that oscillates through the rotational deformation of the material.
Total Internal Reflection
Phenomenon where light reflects completely within a medium (like optical fiber) when striking at an angle greater than the critical angle.
Traction
Ability of a wheel or tire to grip a surface without sliding to generate motion.
Trade Wind
Constant wind blowing from the tropics toward the equator.
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