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.
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.
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.
Solar Eclipse
Phenomenon where the Moon comes between the Earth and the Sun, obscuring the latter.
Solar Noon
Instant when the Sun crosses the observer’s meridian and reaches its highest point.
Solar Radiation
Energy in the form of light and heat emitted by the Sun that reaches the Earth.
Solar System
Set of planets and other celestial bodies orbiting around the Sun.
Solar Wind
Stream of charged particles released from the upper atmosphere of the Sun.
Solenoid
Cylindrical coil with a uniformly wound conducting wire, whose inductance depends on the formula L = (μ · N² · A) / l.
Solstice
Time when the Sun reaches its maximum or minimum declination relative to the celestial equator.
Solubility
Maximum capacity of a substance to dissolve in a given solvent at a specific temperature.
Solute
Substance that dissolves in another and is generally found in a smaller proportion in a solution.
Solution
Homogeneous mixture at the molecular or ionic level of two or more pure substances that do not react with each other.
Solvation
Process by which solvent molecules surround and attract salt ions, facilitating their dissolution.
Solvent
Substance in which the solute dissolves, determining the physical state of the solution.
Space-Time
Mathematical model combining the three spatial dimensions and the temporal dimension into a single four-dimensional fabric.
Space-Time Curvature
Deformation of the fabric of the universe caused by massive objects, which determines the trajectory of other bodies and light.
Special Relativity
Physical theory describing the motion of bodies in the absence of gravitational fields at speeds close to that of light.
Specular Reflection
Orderly bouncing of light off a smooth surface, where parallel incident rays remain parallel after reflection.
Speed
Scalar quantity representing the distance traveled per unit of time, without considering direction.
Speed of Light
Constant speed of EM waves in a vacuum, approximately 2.99 · 10⁸ m/s, defined by the relationship c = λ · f.
Speed of Light (Limit)
Universal and invariable maximum speed for all observers, regardless of their state of motion.
Spherical Aberration
Optical defect where rays striking far from the axis focus at different points, causing a loss of sharpness.
Spontaneous Emission
Process by which an electron in an excited state returns to a lower level, releasing a photon without external intervention.
Spring Constant
Value indicating a spring’s stiffness, representing the force required to produce a unit of deformation (N/m).
Spring Tide
Phenomenon of maximum tidal range occurring when the Moon and the Sun are aligned (new and full moon).
Standard Atmosphere
Reference model establishing the mean pressure at sea level as 1013.25 hPa (1 atm) at a temperature of 15 °C.
Standard Conditions
Standard set of pressure (1 atm) and temperature (273.15 K) used to compare gas properties.
Standing Wave
Interference pattern formed by the superposition of an incident and a reflected wave, which appears not to travel.
Star
Object in space emitting light and heat, formed by high-temperature gases.
State of Matter
Notation in the equation (s, l, g, aq) indicating whether a substance is solid, liquid, gaseous, or in aqueous solution.
State of Rest
Condition of a body whose velocity is zero relative to a given frame of reference.
States of Matter
Forms of aggregation in which matter exists (solid, liquid, gas, and plasma) depending on the intensity of cohesive forces.
Static Friction
Resistance that prevents the start of sliding of an object at rest.
Statistical Range
A measure of dispersion indicating the difference between the maximum and minimum values of a distribution.
Statistics
The branch of mathematics that develops methods for collecting, organizing, analyzing, and interpreting data to draw valid conclusions.
Stator
Fixed part of an electric machine containing the magnets or coils that generate the magnetic field necessary for operation.
Steady State
Final equilibrium state where the current stabilizes and the inductor ideally behaves as a short circuit.
Stefan-Boltzmann Law
Law stating that the total energy emitted by a black body is proportional to the fourth power of its temperature.
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.
Most visited courses
To learn and experience
Take your knowledge to the next level with science kits and hands-on tools that connect theory with experimentation
Essential for teachers and students
Notion
Organize your notes, tasks, and projects in one place. Notion combines notes, lists, and calendars in one flexible space.
Canva
Design presentations, diagrams, and infographics with easy-to-use templates and professional results
Genially
Create interactive content, presentations, and educational games in a simple and visual way
Desmos
The most intuitive graphing calculator to explore mathematics and create dynamic classroom activities
Tinkercad
Design in 3D and simulate electronic circuits for free; it’s the perfect tool for simple robotics projects
Your Infinite Library
Enjoy the freedom to explore millions of titles and a curated selection of magazines on any device
Join Prime for students and young adults
The best series. Millions of songs. All included with your subscription.
Science made fun
Learn with the best courses
40% off!
Coursera
Courses from leading universities and companies. Learn practical skills and earn professional certifications
edX
Online courses from leading universities and companies. Learn practical skills and earn professional certifications
Udemy
Thousands of online courses tailored to your level. Learn at your own pace with expert instructors