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.
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.
Half-life
Time required for half of the nuclei in a radioactive sample to decay into a different element.
Harmonics
Sinusoidal components of the series whose frequencies are integer multiples of the fundamental frequency.
Heat
Thermal energy in transit from one body to another. It is measured in Joules (J), though the calorie (cal) is used, where 1 cal = 4.184 J.
Height
The perpendicular distance measured from the base to the furthest point or vertex of a figure.
Heliocentric Model
Astronomical theory that places the Sun at the center of the system and the planets revolving around it.
High Tide
The moment when sea water reaches its maximum height within the tidal cycle; it is measured in meters (m) or feet (ft) relative to the mean level.
Hohmann Transfer Orbit
Orbital maneuver that uses two engine pulses to move a spacecraft between two circular orbits.
Homologous Series
Group of organic compounds with the same chemical function that differ only by the number of methylene groups.
Hooke’s Law
Physical principle stating that the force exerted by a spring is proportional to its deformation, measured in joules (J) regarding work performed.
Horizontal Displacement
Change in position of an object measured exclusively along the axis parallel to the horizon.
Hydration
Ability of some salts to incorporate water molecules into their crystal structure in a constant manner.
Hydraulic Press
Device that multiplies a force through the area ratio F1 / A1 = F2 / A2, based on Pascal’s principle.
Hydride
Chemical compound formed by the combination of hydrogen with any other element, whether metallic or non-metallic.
Hydrogen
Chemical element with atomic number 1, the lightest in the periodic table, which under normal conditions occurs as a diatomic gas (H₂).
Hydrogen Bond
Especially strong dipole-dipole interaction between the hydrogen atom of one water molecule and the oxygen of another.
Hydrostatic Pressure
Pressure due to the weight of a fluid at rest, calculated as P = ρ · g · h and measured in Pascals (Pa) in the SI.
Hygrometer
Precision instrument designed to measure the moisture content in the atmosphere.
Hyperopia
Visual defect where images are focused behind the retina; it is corrected through the use of convex lenses.
Hypocenter
Point inside the Earth where the rupture that generates the seism originates; its depth is measured in kilometers (km).
Hypotenuse
The longest side in a right triangle, opposite the right angle.
Ice Sheet
A mass of glacial ice covering more than 50,000 km² of land and flowing in all directions (e.g., Antarctica and Greenland).
Ideal Gas
Theoretical gas composed of point particles with random displacements that do not interact with each other, following the gas laws.
Ideal Gas Law
Equation of state relating pressure, volume, temperature, and moles of a gas through the expression PV = nRT.
Image of a Point
The specific value returned by the function when evaluated at a concrete value within its domain.
Impact Force
Intense force acting over a very short period of time, characteristic of collisions and crashes.
Impedance
Total opposition a circuit offers to the flow of alternating current; it combines resistance and reactances, measured in Ohms (Ω).
Improper Fraction
A fraction whose numerator is equal to or greater than the denominator, indicating the value is equal to or greater than one whole.
Impulse
Vector quantity product of the applied force by the time interval of action, measured in N·s.
Impulse-Momentum Theorem
Physical relationship stating that the impulse applied to a body equals the change in its linear momentum.
Incident Ray
Light beam that propagates toward a reflective surface before interacting with it.
Inclination
Degree of deviation of a surface or line from the horizontal or vertical.
Inclined Plane
Flat surface forming an angle with the horizontal plane, used to raise or lower bodies with less effort.
Incompressible Fluid
Substance whose density is assumed constant (ρ = constant in the SI) under pressure changes, such as most liquids.
Increment (Δx)
The difference or variation between two values of the independent variable used to calculate the rate of change.
Independence of Motions
Principle that allows decomposing a complex motion into simultaneous simple motions that do not interfere with each other.
Independent Event
An event whose probability of occurrence is not affected by the previous outcome of another distinct event.
Metallic Bond
Electrostatic attraction between a lattice of metallic cations and a cloud” of delocalized electrons that move freely.”
Methane
Potent greenhouse gas produced by organic decomposition and agricultural activities.
Microgravity
Condition of apparent weightlessness experienced by objects in free fall or orbit.
Mixed Circuit
Configuration that combines series and parallel connections within the same electrical network.
Mixed Number
A notation that combines a whole number and a proper fraction to easily represent values greater than one unit.
Mixture
Combination of two or more substances that retain their individual properties.
Mode
The value or category that appears most frequently within a data distribution.
Modern Physics
Branch of physics studying quantum physics, relativity, and other advanced phenomena.
Molality
Concentration unit that expresses the number of moles of solute per kilogram of solvent (mol/kg).
Molarity
Concentration unit that expresses the number of moles of solute per liter of solution (mol/L).
Mole Fraction
Dimensionless ratio between the number of moles of one component and the total number of moles of all components in the solution.
Molecular Formula
Chemical expression indicating the exact number and type of atoms that make up a specific molecule.
Molecular Geometry
Spatial arrangement of atoms in a molecule, determined by bond angles and distances between nuclei.
Molecular Structure
Three-dimensional arrangement of the atoms that constitute a molecule and the nature of their spatial organization.
Molecule
Smallest particle of a substance that retains its chemical properties, formed by two or more bonded atoms.
Moment of a Force
Quantity that measures the ability of a force to produce a rotation around a point or axis.
Momentum
Vector quantity defined as the product of a body’s mass and its velocity, measured in kg·m/s.
Monsoon
Seasonal wind causing drastic changes in precipitation and temperatures.
Moraine
Accumulation of sediment and rocks (till) transported and deposited directly by the movement of a glacier.
Mount
Mechanical system that supports the telescope and allows its movement to point at and track celestial objects.
Mountain Glacier
A mass of ice confined by mountainous terrain, flowing from cirques into valleys; also called an alpine glacier.
Movable Pulley
Device whose axle can move, allowing the applied force to be less than the resistance.
Multimeter
Versatile instrument capable of measuring multiple electrical quantities such as voltage, current, and resistance in a single device.
Mutually Exclusive Events
A pair of events that cannot occur simultaneously in a single trial of a random experiment.
Myopia
Visual condition where distant objects are focused in front of the retina; it is corrected through the use of concave lenses.
Nadir
Point on the celestial sphere opposite to the zenith, located directly below the observer’s feet.
Natural Cycle
Periodic process in nature, like the water or carbon cycle.
Natural Hazard
Ciencias Ambientales
Natural hazard
A potential hazard arising from natural phenomena that may affect people or property.
Natural Radioactivity
Phenomenon present in nature due to unstable isotopes existing in the Earth’s crust or produced by cosmic rays.
Natural Resource
Ciencias Ambientales
Natural resource
A natural resource that is useful to humans, whether renewable or non-renewable
Natural Satellite
Solid celestial body that orbits around a planet of greater mass.
Neap Tide
Phenomenon of minimum tidal range occurring when the Moon and the Sun form a right angle relative to the Earth.
Negative Acceleration (Deceleration)
Change in velocity where its value decreases over time, also known as braking.
Negative Numbers
Values less than zero located to the left of the origin; they represent debts, decreases, or opposite directions in physics.
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.
Stellar Radiation
Energy emitted by stars, primarily in the form of visible, ultraviolet, and infrared light.
Step-by-step Analysis
Resolution strategy that divides the mixed circuit into identifiable sections as purely series or purely parallel.
Stoichiometric Coefficient
Number placed in front of chemical formulas in an equation to indicate the relative proportion of molecules or moles.
Storage Capacity
Total amount of electrical charge (usually in Ah) that a battery can supply based on the mass of its internal reactants.
Stored Energy
Electric potential energy accumulated in the field between the plates, calculated using the formula U = 1/2 · C · V² in the SI (in Joules).
Stratosphere
Layer located above the troposphere containing the ozone layer; in it, temperature increases with altitude.
Streamline
Imaginary path followed by a fluid particle during steady flow.
String Tension
Pulling force exerted on the string that determines wave speed through the relationship v = √(T / μ).
Structural Color
Color produced by the interaction of light with physical microstructures (as in iridescence) instead of chemical pigments.
Sublimation
Phase change in which a solid substance passes directly to the gaseous state without passing through the liquid state.
Subscript
Small number indicating the amount of atoms of a specific element present in a molecule or compound.
Substance
Type of matter with defined composition and characteristic properties allowing it to be distinguished from others.
Subtractive Synthesis
Creation of colors through the absorption (subtraction) of wavelengths by pigments or filters, characteristic of the CMYK model.
Sunspot
Region of the photosphere with lower temperature and intense magnetic activity.
Superposition
Principle according to which a quantum system can exist in a combination of all its possible states simultaneously until it is observed.
Superposition Principle
Law stating that the resultant displacement at a point is the algebraic sum of the displacements of the individual waves.
Surface
The outer extent of a body or figure that possesses only two dimensions (length and width). its standard SI unit is the square meter (m²) and in the imperial system the square foot (ft²).
Surface Tension
Attraction force between the molecules on the water surface that creates a resistant layer.
Switch
Control device that allows opening or closing the path of the electric current at a point in the circuit.
Symmetric Property
A property that allows swapping the members of an equality without altering its validity or logical meaning.
Synchronous Rotation
Phenomenon where the Moon takes the same time to rotate and orbit, always showing the same side.
Synodic Month
Time it takes for the Moon to show the same phase again, approximately 29.5 days.
Synthesis Reaction
Type of reaction where two or more pure substances combine to form a single, more complex product.
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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