STEM OnLine Mini Dictionary
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.
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.
Ohmic Material
One that exhibits a constant linear relationship between the applied voltage and the resulting current, keeping its resistance fixed.
Ohmmeter
Device for measuring electrical resistance; it should only be used on components that are not energized.
Oort Cloud
Giant spherical region of icy objects surrounding the solar system.
Open Circuit
Interruption in the conducting path that prevents the flow of electric current through the circuit.
Opening
Diameter of a telescope’s primary objective, which determines its light-gathering capacity.
Operating Autonomy
Duration during which the system can generate energy, limited in conventional batteries by their reactants and in fuel cells by the external supply.
Optical Center
Central point of a lens through which light rays pass without undergoing any deviation in their trajectory.
Optical Power (Diopter)
Measure of a lens’s ability to converge light, calculated as the inverse of its focal length in meters.
Optical Transmission
Process by which light passes through a material medium without being absorbed or reflected, maintaining part of its original energy.
Optics
Branch of physics studying light and related phenomena.
Orbit
Curved path followed by a physical object around another under the influence of gravity.
Orbital Elements
Set of parameters required to uniquely identify a specific orbit.
Orbital Inclination
Angle between the orbital plane and a reference plane such as the equator.
Orbital Period
Time it takes for a planet to complete one full revolution around the Sun.
Orbital Perturbation
Variation in a body’s orbit caused by external forces such as radiation pressure or the gravity of other bodies.
Orbital Velocity
Speed required to maintain a stable orbit around a celestial body.
Order Relation
A property that allows comparing two numbers to determine which is greater, lesser, or equal, establishing a positional hierarchy.
Ordered Pair
A set of two numbers where the order is critical for locating a specific point in two-dimensional space.
Ordinate Axis
The vertical line in the Cartesian plane, generally represented by the variable $y$.
Organic Chemistry
Branch of chemistry studying carbon-based compounds and their transformations.
Origin
The central reference point on a line or plane, represented by the number 0, from which all distances are measured.
Origin of Coordinates
The intersection point of the axes $(0,0)$ where the value of both variables is zero.
Orthogonal Vectors
A set of vectors that form a 90° angle with each other, having a dot product equal to zero.
Oscillation
Repetitive back-and-forth motion of a body passing through an equilibrium position.
Oscillation Frequency
Number of complete cycles the system performs per unit of time.
Outer Planet
Giant planet located beyond the asteroids: Jupiter, Saturn, Uranus and Neptune.
Outlier
A numerical observation that lies significantly far from the rest of the data, potentially distorting the arithmetic mean.
Output Voltage
Voltage obtained across the terminals of one of the resistors in a divider, calculated to power another part of a circuit.
Overfitting
An error where the model fits the random fluctuations of the data too closely, losing the ability to predict new values.
Overpotential
Excess voltage required, beyond the thermodynamic potential, to overcome the kinetic barriers of a reaction at the electrode.
Ozone Layer
Region of the stratosphere with a high concentration of ozone gas ($O_3$) that filters out most solar ultraviolet radiation.
Product
Substance formed as a result of a chemical reaction, written to the right of the arrow in the equation.
Projectile Motion
Two-dimensional motion whose curved trajectory results from the combination of a uniform horizontal advance and a vertical free fall.
Proof
Logical reasoning establishing the truth of a theorem or mathematical proposition.
Propagation Speed
Speed at which the perturbation travels, defined by the product of frequency and wavelength.
Proper Fraction
A type of fraction where the numerator is smaller than the denominator, always representing a value less than one whole unit.
Proportion
A statement of equality between two ratios, ensuring that the relationship between magnitudes remains constant on both sides.
Proportionality Constant
A fixed value relating two magnitudes; obtained by dividing any pair of corresponding values in a relationship.
Protection Elements
Components designed to interrupt the circuit in case of overload or short circuit to prevent damage (fuses, circuit breakers).
Proton
Subatomic particle with a positive electrical charge of 1.602 × 10⁻¹⁹ C located in the atom’s nucleus.
Pulley
Simple machine consisting of a grooved wheel that rotates on an axle, used to move bodies; the work performed is measured in joules (J).
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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