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🧲AP Physics 2
Key Terms

540 essential vocabulary terms and definitions to know for your AP Physics 2 exam

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🧲AP Physics 2
Key Terms by Unit

📚Unit 9 – Thermodynamics

9.1 Kinetic Theory of Temperature and Pressure

TermDefinition
atomic motionThe movement and collisions of atoms within a gas that produce forces and pressure.
average kinetic energyThe mean kinetic energy of all atoms in a system, which characterizes the temperature of that system.
collisionsInteractions between gas atoms or between atoms and container surfaces that involve the exchange of momentum and forces.
conservation of momentumA principle stating that the total momentum of an isolated system remains constant in the absence of external forces.
ideal gasA theoretical gas whose atoms follow the kinetic theory model and obey the relationship between temperature, kinetic energy, and molecular speed.
Maxwell-Boltzmann distributionA graphical representation showing the distribution of energies and speeds of atoms at a given temperature.
perpendicular componentsThe components of forces exerted by gas atoms that are directed perpendicular to a surface, which contribute to pressure.
pressureThe force per unit area exerted by a gas on a surface, resulting from collisions of gas atoms with that surface.
root-mean-square speedThe speed corresponding to the average kinetic energy of atoms in an ideal gas, related to temperature by the equation v_rms = √(3k_B T/m).
temperatureA measure of the average kinetic energy of the atoms within a system.

9.2 The Ideal Gas Law

TermDefinition
absolute zeroThe temperature at which an ideal gas would have zero pressure, extrapolated from a graph of pressure versus temperature.
elastic collisionA collision between gas atoms in which kinetic energy is conserved, a key assumption in the ideal gas model.
ideal gasA theoretical gas whose atoms follow the kinetic theory model and obey the relationship between temperature, kinetic energy, and molecular speed.
instantaneous velocitiesThe random velocities of individual gas atoms at any given moment, assumed to vary randomly in the ideal gas model.
molesA unit of measurement for the amount of substance, representing the number of particles in a gas sample used in the ideal gas law.
pressureThe force per unit area exerted by a gas on a surface, resulting from collisions of gas atoms with that surface.
temperatureA measure of the average kinetic energy of the atoms within a system.
volumeThe space occupied by a gas, one of the key variables in the ideal gas law.

9.3 Thermal Energy Transfer and Equilibrium

TermDefinition
conductionA thermal process by which energy is transferred between systems or within a system through direct contact without bulk motion of material.
convectionA thermal process by which energy is transferred through the bulk motion of a fluid (liquid or gas).
coolingThe transfer of energy out of a system through thermal processes.
heatingThe transfer of energy into a system through thermal processes.
radiationA thermal process by which energy is transferred through electromagnetic waves without requiring a medium.
temperature differenceThe difference in thermal energy between two systems that drives the spontaneous transfer of energy from the higher-temperature system to the lower-temperature system.
thermal contactA condition where two systems are positioned such that thermal processes can transfer energy between them.
thermal equilibriumA state in which an object maintains a constant temperature and emits energy at the same rate it absorbs energy.

9.4 The First Law of Thermodynamics

TermDefinition
adiabatic processA thermodynamic process in which no energy is transferred to or from the system through thermal processes.
center of massThe point that represents the average position of all the mass in a system.
closed systemA system that can exchange energy with its surroundings but not matter.
conservative forcesForces for which the work done is independent of the path taken, such as gravitational and electrostatic forces.
first law of thermodynamicsA restatement of conservation of energy that accounts for energy transferred into or out of a system by work, heating, or cooling.
ideal gasA theoretical gas whose atoms follow the kinetic theory model and obey the relationship between temperature, kinetic energy, and molecular speed.
internal energyThe sum of the kinetic energy and potential energy of all the objects and their configurations that make up a system.
isobaric processA thermodynamic process in which the pressure of a system remains constant.
isolated systemA system that does not exchange energy or matter with its surroundings.
isothermA line of constant temperature on a pressure-volume diagram.
isothermal processA thermodynamic process in which the temperature of a system remains constant.
isovolumetric processA thermodynamic process in which the volume of a system remains constant.
kinetic energyThe energy of motion possessed by an object due to its velocity.
monatomic gasAn ideal gas composed of single atoms rather than molecules.
potential energyThe energy stored in the configuration or arrangement of objects within a system.
PV diagramA pressure-volume graph used to represent and visualize thermodynamic processes.
thermodynamic processesProcesses that describe how a system changes in terms of pressure, volume, temperature, and internal energy.
work done on a systemEnergy transferred to a system through mechanical means, calculated as W = -PΔV for constant or average external pressure.

9.5 Specific Heat and Thermal Conductivity

TermDefinition
conductionA thermal process by which energy is transferred between systems or within a system through direct contact without bulk motion of material.
intrinsic propertyA characteristic of a material that is independent of the amount of material present and depends on the arrangement and interactions of its atoms.
rate of energy transferThe amount of thermal energy transferred per unit time, measured in watts or joules per second.
specific heatAn intrinsic property of a material that quantifies the amount of energy required to change the temperature of a unit mass of that material by one degree.
temperature changeThe difference in temperature of an object, represented as ΔT, which is directly related to the energy required to heat or cool the object.
temperature differenceThe difference in thermal energy between two systems that drives the spontaneous transfer of energy from the higher-temperature system to the lower-temperature system.
thermal conductivityAn intrinsic property of a material that describes how readily heat energy is transferred through it by conduction.

9.6 Entropy and the Second Law of Thermodynamics

TermDefinition
closed systemA system that can exchange energy with its surroundings but not matter.
entropyA measure of the tendency of energy to spread out or disperse, and the unavailability of some of a system's energy to do work.
isolated systemA system that does not exchange energy or matter with its surroundings.
localized energyEnergy concentrated in a specific region or form that tends to disperse and spread out over time.
reversible processA process in which a system can return to its original state without any net change in entropy of the universe.
second law of thermodynamicsThe principle stating that the total entropy of an isolated system can never decrease and remains constant only when all processes are reversible.
state functionA property of a system that depends only on the current state or configuration of the system, not on how the system reached that state.
thermodynamic equilibriumThe state in which a system has maximum entropy and no net changes occur in its macroscopic properties.

📚Unit 10 – Electric Force, Field, and Potential

10.1 Electric Charge and Electric Force

TermDefinition
attractive forceThe electrostatic force exerted between two objects with opposite charges, pulling them together.
chargeA fundamental property of matter that can be positive or negative, determining how objects interact electromagnetically.
charge carrierParticles that carry electric charge through a medium, such as electrons in a wire.
conductorA material through which electric charge can move, with resistivity that typically increases with temperature.
contact forcesNonfundamental forces such as normal force, friction, and tension that result from the combined effect of many electric interactions between particles.
Coulomb's lawThe law stating that the electrostatic force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
electric fieldA vector quantity that represents the electric force per unit charge exerted at a given point in space, originating from charged objects.
electric forceThe force exerted on a charged object by an electric field.
electric permittivityA measurement of the degree to which a material or medium is polarized in the presence of an electric field.
electric polarizationThe induced rearrangement of electrons by an external electric field, resulting in a separation of positive and negative charges within a material or medium.
electrically neutralA state in which an object or system has equal amounts of positive and negative charge, resulting in no net electric charge.
electrostatic forceThe force exerted between charged objects due to their electric charges, described by Coulomb's law and dependent on the magnitude and signs of the charges.
elementary chargeThe magnitude of charge carried by a single electron or proton, denoted as e, representing the smallest indivisible amount of charge.
free spaceA vacuum or empty space with a constant value of electric permittivity denoted as ε₀.
gravitational forceForces that result from the mass of objects and are always attractive in nature.
insulatorMaterials that do not allow electric charge to move freely and can retain charge in localized regions.
point chargeAn idealized model of a charged object treated as having all its charge concentrated at a single location in space.
repulsive forceThe electrostatic force exerted between two objects with charges of the same sign, pushing them apart.

10.2 The Process of Charging

TermDefinition
charge distributionThe spatial arrangement or pattern of electric charges within a system or on an object.
conservation of chargeThe principle that the total electric charge in an isolated system remains constant over time.
contactA process by which charge can be transferred between two systems through direct touching.
electronNegatively charged particles that serve as the primary charge carriers in most common electrical circuits.
electrostatic forceThe force exerted between charged objects due to their electric charges, described by Coulomb's law and dependent on the magnitude and signs of the charges.
frictionA process by which charge can be transferred between two systems through rubbing or contact.
groundingThe process of electrically connecting a charged system to a much larger neutral system, such as Earth, to neutralize its charge.
induced charge separationThe redistribution of charges within a neutral or charged system caused by the electrostatic force from a nearby charged object, resulting in polarization.
net chargeThe total amount of electric charge in a system, calculated as the sum of all positive and negative charges.
polarizationThe process by which charges within a neutral system become separated, with positive charges shifting in one direction and negative charges in another.
transfer of chargeThe movement of electric charge from one system to another, typically involving the movement of electrons.

10.3 Electric Fields

TermDefinition
charged conductorsMaterials that allow electric charge to move freely throughout them and can be given a net electric charge.
charged objectAn object that possesses electric charge and can interact with electric and magnetic fields.
electric fieldA vector quantity that represents the electric force per unit charge exerted at a given point in space, originating from charged objects.
electric field line diagramsSimplified models of electric field maps that use lines to represent the direction and relative magnitude of the electric field.
electric forceThe force exerted on a charged object by an electric field.
electrostatic equilibriumA state in which charges are at rest and there is no net motion of charge within a conductor or insulator.
excess chargeThe net charge on an object beyond its neutral state.
insulatorMaterials that do not allow electric charge to move freely and can retain charge in localized regions.
negative chargeA charge toward which electric field lines converge.
net electric fieldThe vector sum of individual electric fields created by multiple charged objects at a given location.
perpendicular to the surfaceThe orientation of the electric field at the surface of a charged conductor, pointing directly away from or toward the surface at a 90-degree angle.
point chargeAn idealized model of a charged object treated as having all its charge concentrated at a single location in space.
positive chargeA charge from which electric field lines radiate outward.
spherically symmetric charge distributionA charge arrangement that is uniform in all directions from a central point, such as on a sphere.
surface charge distributionThe arrangement of electric charge on the outer surface of a conductor in electrostatic equilibrium.
test chargeA point charge of small enough magnitude that its presence does not significantly affect the electric field it is used to measure.
vector field mapA visual representation showing vectors at various points in space to illustrate the magnitude and direction of a field quantity.
vector quantityA physical quantity that has both magnitude and direction.

10.5 Electric Potential

TermDefinition
conductorA material through which electric charge can move, with resistivity that typically increases with temperature.
configuration of charged objectsAn arrangement of multiple charged particles or objects whose combined electric potential can be determined.
electric fieldA vector quantity that represents the electric force per unit charge exerted at a given point in space, originating from charged objects.
electric field vector mapA representation of an electric field using vectors to show the magnitude and direction of the field at various points in space.
electric potentialA scalar quantity that represents the electric potential energy per unit charge at a point in space, measured in volts.
electric potential differenceThe difference in electric potential energy per unit charge between two points in a circuit, measured in volts; also called voltage.
electrical contactA physical connection between conductors that allows charge redistribution.
equipotential lineLines in space that connect points of equal electric potential; also called isolines of electric potential.
isolineLines that connect points of equal value of a quantity; in this context, lines of equal electric potential.
isoline mapA representation of a field using lines that connect points of equal potential or other equal values.
point chargeAn idealized model of a charged object treated as having all its charge concentrated at a single location in space.
scalar superpositionThe principle that the total electric potential at a point due to multiple point charges is the sum of the potentials due to each individual charge.
test chargeA point charge of small enough magnitude that its presence does not significantly affect the electric field it is used to measure.

10.6 Capacitors

TermDefinition
capacitanceA measure of the ability of a capacitor to store charge, defined as the ratio of the magnitude of charge stored on each plate to the electric potential difference between them.
chargeA fundamental property of matter that can be positive or negative, determining how objects interact electromagnetically.
constant accelerationMotion in which the velocity changes at a constant rate, as experienced by a charged particle between oppositely charged parallel plates.
dielectricAn insulating material placed between the plates of a capacitor that can be polarized by an electric field and increases the capacitance.
dielectric constantA dimensionless property of a material that describes how effectively it can be polarized by an electric field; represented by the symbol κ.
electric fieldA vector quantity that represents the electric force per unit charge exerted at a given point in space, originating from charged objects.
electric permittivity of free spaceA fundamental physical constant that describes the ability of empty space to support an electric field; represented by the symbol ε₀.
electric potential differenceThe difference in electric potential energy per unit charge between two points in a circuit, measured in volts; also called voltage.
electric potential energyThe energy stored in a system due to the position of a charged object in an electric field, dependent on the charge and electric potential.
parallel-plate capacitorA capacitor consisting of two separated parallel conducting surfaces that hold equal amounts of charge with opposite signs.
plate areaThe surface area of one of the conducting plates in a parallel-plate capacitor.
plate separationThe distance between the two parallel conducting plates in a capacitor.

10.7 Conservation of Electric Energy

TermDefinition
charged objectAn object that possesses electric charge and can interact with electric and magnetic fields.
conservation of energyThe principle that the total energy in an isolated system remains constant, with energy transforming between different forms but not being created or destroyed.
electric potentialA scalar quantity that represents the electric potential energy per unit charge at a point in space, measured in volts.
electric potential energyThe energy stored in a system due to the position of a charged object in an electric field, dependent on the charge and electric potential.
kinetic energyThe energy of motion possessed by an object due to its velocity.

📚Unit 11 – Electric Circuits

11.1 Electric Current

TermDefinition
chargeA fundamental property of matter that can be positive or negative, determining how objects interact electromagnetically.
charge carrierParticles that carry electric charge through a medium, such as electrons in a wire.
conventional currentThe direction of electric current flow defined as the movement of positive charges from the positive terminal to the negative terminal of a power source.
currentThe flow of electric charge through a conductor, measured in amperes (A).
electric potential differenceThe difference in electric potential energy per unit charge between two points in a circuit, measured in volts; also called voltage.
electromotive forceThe energy per unit charge provided by a source such as a battery to move charge through a circuit; abbreviated as emf (ε).
electronNegatively charged particles that serve as the primary charge carriers in most common electrical circuits.

11.2 Simple Circuits

TermDefinition
circuitA closed or open path composed of electrical loops and circuit elements through which electric charge may flow.
circuit elementA component in an electric circuit, such as a resistor or bulb, through which current flows and across which a potential difference exists.
circuit schematicA diagram used to represent and analyze electric circuits using standardized symbols for circuit elements.
closed circuitA circuit in which charges are able to flow through a complete path.
conventional currentThe direction of electric current flow defined as the movement of positive charges from the positive terminal to the negative terminal of a power source.
electric potential differenceThe difference in electric potential energy per unit charge between two points in a circuit, measured in volts; also called voltage.
electrical loopA closed path in a circuit through which charges may flow.
open circuitA circuit in which charges are not able to flow due to a break in the path.
short circuitA circuit in which charges flow with no change in potential difference.

11.3 Resistance, Resistivity, and Ohm's Law

TermDefinition
chargeA fundamental property of matter that can be positive or negative, determining how objects interact electromagnetically.
conductorA material through which electric charge can move, with resistivity that typically increases with temperature.
cross-sectional areaThe area of a cross-section of a conductor, which is inversely proportional to its resistance.
currentThe flow of electric charge through a conductor, measured in amperes (A).
electric potential differenceThe difference in electric potential energy per unit charge between two points in a circuit, measured in volts; also called voltage.
electrical characteristicsThe properties of circuit elements that describe how they respond to and affect electric current and voltage, including resistance and conductivity.
Ohm's lawThe relationship stating that current through a conductive element is directly proportional to the potential difference across it and inversely proportional to its resistance (I = ΔV/R).
ohmic materialsMaterials that obey Ohm's law and maintain constant resistance regardless of the current flowing through them.
resistanceThe opposition to the flow of electric current through a material or circuit element.
resistivityAn intrinsic property of a material that measures its resistance to electric current flow; remains constant for ohmic materials regardless of temperature.
resistorCircuit elements designed to provide resistance to current flow and convert electrical energy into thermal energy.
thermal energyThe energy produced when a resistor converts electrical energy, which can increase the temperature of the resistor and its surroundings.

11.4 Electric Power

TermDefinition
brightnessThe luminous intensity of a bulb, which increases with the power dissipated by the bulb.
circuit elementA component in an electric circuit, such as a resistor or bulb, through which current flows and across which a potential difference exists.
currentThe flow of electric charge through a conductor, measured in amperes (A).
electric potential differenceThe difference in electric potential energy per unit charge between two points in a circuit, measured in volts; also called voltage.
energy transferThe movement of energy into, out of, or within an electric circuit through the work done by electric forces.
powerThe rate at which energy is transferred, converted, or dissipated in an electric circuit, measured in watts.

11.6 Kirchhoff's Loop Rule

TermDefinition
closed loopA complete path in a circuit that starts and ends at the same point, allowing current to flow continuously.
conservation of energyThe principle that the total energy in an isolated system remains constant, with energy transforming between different forms but not being created or destroyed.
electric potentialA scalar quantity that represents the electric potential energy per unit charge at a point in space, measured in volts.
electric potential differenceThe difference in electric potential energy per unit charge between two points in a circuit, measured in volts; also called voltage.
Kirchhoff's loop ruleA principle stating that the sum of potential differences across all circuit elements in a single closed loop must equal zero, based on conservation of energy.

11.7 Kirchhoff's Junction Rule

TermDefinition
conservation of chargeThe principle that the total electric charge in an isolated system remains constant over time.
currentThe flow of electric charge through a conductor, measured in amperes (A).
junctionA point in a circuit where two or more conductors meet, allowing current to split or combine.
Kirchhoff's junction ruleA principle stating that the total electric charge entering a junction per unit time equals the total charge exiting that junction per unit time, based on conservation of electric charge.

11.8 Resistor-Capacitor (RC) Circuits

TermDefinition
capacitor in parallelCapacitors connected with all positive plates connected together and all negative plates connected together, where the equivalent capacitance equals the sum of individual capacitances.
capacitor in seriesCapacitors connected end-to-end in a single path, where the same charge accumulates on each capacitor and the equivalent capacitance is less than the smallest individual capacitance.
charging capacitorA capacitor in a circuit that is accumulating charge on its plates, with increasing potential difference and decreasing current over time until reaching steady state.
conservation of chargeThe principle that the total electric charge in an isolated system remains constant over time.
discharging capacitorA capacitor in a circuit that is releasing stored charge from its plates, with decreasing potential difference, charge, and current over time until reaching steady state.
electric potential energy stored in the capacitorThe energy stored in a capacitor due to the separation of charge on its plates, which changes during charging and discharging and approaches a constant value at steady state.
equivalent capacitanceThe single capacitance value that can replace a collection of capacitors in a circuit while maintaining the same electrical behavior.
fully chargedThe state of a capacitor after a long charging time when it has reached maximum potential difference and zero current flows in the circuit branch containing it.
potential difference across a capacitorThe voltage between the plates of a capacitor, which changes over time during charging and discharging and asymptotically approaches a steady-state value.
RC circuitA circuit containing a resistor and capacitor in combination, where the capacitor charges or discharges through the resistor over time.
steady stateA condition reached after a long time interval where the potential difference across a capacitor and current in the circuit branch remain constant.
time constantA measure of how quickly a capacitor charges or discharges in an RC circuit, defined as τ = R_eq × C_eq, representing the time for charge to reach approximately 63% of final value when charging or 37% of initial value when discharging.

📚Unit 12 – Magnetism and Electromagnetism

12.1 Magnetic Fields

TermDefinition
bar magnetA permanent magnet with distinct north and south poles that produces a magnetic field with closed field lines.
diamagnetismA property of all materials in which their electronic structure creates a weak alignment of dipole moments opposite to an external magnetic field.
Earth's magnetic fieldThe magnetic field generated by Earth that can be approximated as a magnetic dipole field.
external magnetic fieldA magnetic field applied to a material from an outside source.
ferromagnetic materialMaterials such as iron, nickel, and cobalt that can be permanently magnetized by an external field through alignment of magnetic domains.
free spaceA vacuum or empty space with a constant value of electric permittivity denoted as ε₀.
induced magnetismA system property resulting from the alignment of magnetic dipoles within a material in response to an external magnetic field.
magnetic dipoleA pair of equal and opposite magnetic poles that together produce a magnetic field.
magnetic domainRegions within a ferromagnetic material where atomic magnetic dipoles are aligned in the same direction.
magnetic fieldA vector field that exerts a force on moving electric charges, electric currents, and magnetic materials.
magnetic field lineLines used to represent the direction and strength of a magnetic field; they form closed loops and never begin or end.
magnetic forceThe force exerted by a magnetic field on a moving electric charge, electric current, or magnetic material.
magnetic monopoleA hypothetical isolated magnetic charge that does not exist in nature; magnetic fields are only produced by dipoles.
magnetic permeabilityA measurement of the amount of magnetization in a material in response to an external magnetic field.
magnetic poleThe regions at the ends of a magnetic dipole where magnetic field lines emerge (north pole) or enter (south pole).
magnetizationThe process by which a material becomes magnetized in response to an external magnetic field.
north poleThe end of a magnetic dipole from which magnetic field lines point outward.
paramagnetic materialMaterials such as aluminum, titanium, and magnesium that interact weakly with an external magnetic field and do not retain alignment after the field is removed.
permanent magnetismA system property resulting from the alignment of magnetic dipoles within a material that persists without an external magnetic field.
south poleThe end of a magnetic dipole to which magnetic field lines return.
vacuum permeabilityThe constant value of magnetic permeability in free space, represented by the symbol μ₀, that appears in equations representing physical relationships.
vector fieldA representation of a field where each point in space is assigned a vector quantity, such as direction and magnitude.
vector field mapA visual representation showing vectors at various points in space to illustrate the magnitude and direction of a field quantity.

12.2 Magnetism and Moving Charges

TermDefinition
chargeA fundamental property of matter that can be positive or negative, determining how objects interact electromagnetically.
charged objectAn object that possesses electric charge and can interact with electric and magnetic fields.
conductorA material through which electric charge can move, with resistivity that typically increases with temperature.
electric fieldA vector quantity that represents the electric force per unit charge exerted at a given point in space, originating from charged objects.
Hall effectThe phenomenon in which a potential difference is created across a conductor when an external magnetic field perpendicular to the direction of charge motion is applied.
magnetic fieldA vector field that exerts a force on moving electric charges, electric currents, and magnetic materials.
magnetic forceThe force exerted by a magnetic field on a moving electric charge, electric current, or magnetic material.
perpendicularAt a 90-degree angle; the magnetic field direction is perpendicular to both the velocity vector and the position vector from the charged object.
position vectorA vector drawn from a moving charged object to a point in space, used to determine the magnetic field direction at that point.
right-hand ruleA method for determining the direction of magnetic force, current, or magnetic field using the orientation of the right hand.
velocityThe rate and direction of motion of a charged object, which affects the magnitude and direction of the magnetic field it produces.

12.3 Magnetism and Current-Carrying Wires

TermDefinition
concentric circleCircles that share the same center point, used to represent the geometry of magnetic field lines around a straight wire.
current-carrying loopA circular or closed path through which electric current flows, producing a magnetic field along its axis.
current-carrying wireA conductor through which electric current flows, producing a magnetic field around it.
magnetic fieldA vector field that exerts a force on moving electric charges, electric currents, and magnetic materials.
magnetic field vectorArrows representing the magnitude and direction of the magnetic field at specific points in space.
magnetic forceThe force exerted by a magnetic field on a moving electric charge, electric current, or magnetic material.
perpendicular distanceThe shortest distance from a point to a line or surface, measured at a right angle.
right-hand ruleA method for determining the direction of magnetic force, current, or magnetic field using the orientation of the right hand.
vector additionThe mathematical process of combining two or more vectors to find a resultant vector, used to determine net magnetic fields from multiple sources.

12.4 Electromagnetic Induction and Faraday's Law

TermDefinition
area vectorA vector perpendicular to a surface with magnitude equal to the surface's area, used to calculate magnetic flux.
conducting railParallel conductors that form a track along which a conducting rod can move in a magnetic field to generate an induced emf.
conducting rodA rod made of material that allows electric current to flow freely, used in electromagnetic induction applications.
cross-sectional areaThe area of a cross-section of a conductor, which is inversely proportional to its resistance.
Faraday's lawThe principle that an induced emf in a circuit is proportional to the rate of change of magnetic flux through the circuit.
induced electric potential differenceThe voltage generated in a conductor or circuit due to a change in magnetic flux through it.
induced emfThe electromotive force generated in a conductor or circuit due to a changing magnetic flux.
Lenz's lawThe principle that an induced emf creates a current whose magnetic field opposes the change in magnetic flux that produced it.
magnetic fieldA vector field that exerts a force on moving electric charges, electric currents, and magnetic materials.
magnetic fluxA measure of the amount of magnetic field passing through a surface, proportional to the perpendicular component of the magnetic field and the cross-sectional area.
right-hand ruleA method for determining the direction of magnetic force, current, or magnetic field using the orientation of the right hand.
uniform magnetic fieldA magnetic field that has the same magnitude and direction at all points in a region of space.

📚Unit 13 – Geometric Optics

13.1 Reflection

TermDefinition
angle of incidenceThe angle between an incident ray and the normal to a surface.
angle of reflectionThe angle between a reflected ray and the normal to a surface.
coherentDescribing light waves that maintain a constant phase relationship, as produced by a laser.
diffractionThe spreading of a wave around the edges of an obstacle or through an opening.
diffuse reflectionThe reflection of light from a rough surface that scatters light in many different directions due to varying surface normals.
geometric opticsThe study of light behavior using ray diagrams, where the wave nature of light can be neglected.
incident rayA ray of light traveling toward and striking a surface.
interferenceThe phenomenon where the wave nature of light is important and cannot be neglected, involving the superposition of light waves.
law of reflectionThe principle stating that the angle of incidence equals the angle of reflection, both measured from the normal to the surface.
light rayA straight line that is perpendicular to the wavefront of a light wave and points in the direction of travel of the wave.
monochromaticLight consisting of a single wavelength or frequency, as produced by a laser.
normalAn imaginary line perpendicular to a surface at the point where a light ray strikes it.
ray diagramA diagram that depicts the path of light before and after an interaction with matter.
reflected rayA ray of light that bounces off a surface after reflection.
reflectionThe bouncing of light off a surface back into the medium from which it came.
rough surfaceA surface with irregularities that cause diffuse reflection of light.
smooth surfaceA surface with minimal irregularities that causes specular reflection of light.
specular reflectionThe reflection of light from a smooth surface that reflects light uniformly in a single direction due to a constant surface normal.
wavefrontA surface of constant phase in a propagating wave, perpendicular to the direction of wave propagation.

13.2 Images Formed by Mirrors

TermDefinition
center of curvatureThe center point of the sphere from which a spherical mirror is curved, located on the principal axis at a distance equal to twice the focal length.
concave mirrorA converging mirror with a curved surface that reflects inward, causing parallel light rays to converge at a focal point.
convex mirrorA diverging mirror with a curved surface that reflects outward, causing parallel light rays to appear to diverge from a focal point behind the mirror.
focal lengthThe distance from the mirror's surface to its focal point, which determines the location of images formed by the mirror.
focal pointThe point where reflected light rays converge (for concave mirrors) or appear to originate (for convex and plane mirrors).
inverted imageAn image that is flipped relative to the object's orientation.
magnificationThe ratio of the size of an image produced by a mirror to the size of the object, indicating whether the image is enlarged, reduced, or the same size.
plane mirrorA flat mirror that reflects light rays such that the focal point is located at an infinite distance from the mirror.
principal axisThe line passing through the center of a mirror perpendicular to its surface, used as a reference for describing light ray behavior.
principal raysThree specific light rays used in ray diagrams: the ray parallel to the principal axis, the ray reflecting at the center of the mirror, and the ray passing through the focal point.
ray diagramA diagram that depicts the path of light before and after an interaction with matter.
real imageAn image formed when reflected light rays from a common point intersect at another common point, which can be projected onto a screen.
sign conventionsA system of rules used to determine the signs of distances and other quantities relative to the mirror's position and orientation.
upright imageAn image that has the same orientation as the object.
virtual imageAn image formed when reflected light rays diverge such that they appear to have originated from a common point behind the mirror.

13.3 Refraction

TermDefinition
angle of incidenceThe angle between an incident ray and the normal to a surface.
angle of refractionThe angle between a refracted light ray and the normal to a surface.
critical angleThe minimum angle of incidence at which total internal reflection occurs when light travels from a medium with higher index of refraction to one with lower index of refraction.
index of refractionA measure of how much a medium slows down light compared to its speed in vacuum, determining the degree of bending and reflection of light at interfaces.
normalAn imaginary line perpendicular to a surface at the point where a light ray strikes it.
refractionThe change in direction of a light ray as it passes from one medium into another.
Snell's lawThe law relating the angles of incidence and refraction of a light ray passing between two media to their respective indices of refraction, expressed as n₁ sin θ₁ = n₂ sin θ₂.
total internal reflectionThe complete reflection of light back into a medium when light traveling from a denser medium strikes the boundary with a less dense medium at an angle greater than the critical angle.

13.4 Images Formed by Lenses

TermDefinition
concave lensA lens that curves inward and causes parallel light rays to diverge as if they originated from a focal point.
convex lensA lens that curves outward on both sides and converges parallel light rays toward a focal point.
focal lengthThe distance from the mirror's surface to its focal point, which determines the location of images formed by the mirror.
focal pointThe point where reflected light rays converge (for concave mirrors) or appear to originate (for convex and plane mirrors).
inverted imageAn image that is flipped relative to the object's orientation.
magnificationThe ratio of the size of an image produced by a mirror to the size of the object, indicating whether the image is enlarged, reduced, or the same size.
principal axisThe line passing through the center of a mirror perpendicular to its surface, used as a reference for describing light ray behavior.
principal raysThree specific light rays used in ray diagrams: the ray parallel to the principal axis, the ray reflecting at the center of the mirror, and the ray passing through the focal point.
ray diagramA diagram that depicts the path of light before and after an interaction with matter.
real imageAn image formed when reflected light rays from a common point intersect at another common point, which can be projected onto a screen.
sign conventionsA system of rules used to determine the signs of distances and other quantities relative to the mirror's position and orientation.
thin lensA lens whose thickness is negligible compared to its focal length, allowing the use of simplified equations to describe image formation.
thin-lens equationThe equation 1/s_i + 1/s_o = 1/f that relates the image distance, object distance, and focal length of a thin lens.
upright imageAn image that has the same orientation as the object.
virtual imageAn image formed when reflected light rays diverge such that they appear to have originated from a common point behind the mirror.

📚Unit 14 – Waves, Sound, and Physical Optics

14.1 Properties of Wave Pulses and Waves

TermDefinition
amplitudeThe maximum displacement of a wave from its equilibrium position.
compressionA region of high pressure in a longitudinal wave such as a sound wave.
electromagnetic waveA wave consisting of oscillating electric and magnetic fields that are mutually perpendicular and can propagate without requiring a medium.
equilibrium positionThe position of a particle in a wave when it is at rest with no disturbance.
frequencyThe number of complete wave cycles that pass a point per unit time.
longitudinal waveA wave in which particles oscillate parallel to the direction of wave propagation.
mechanical waveA wave that requires a medium to propagate, such as sound or waves on a string.
mediumA material or substance through which a wave travels.
rarefactionA region of low pressure in a longitudinal wave such as a sound wave.
sound waveA mechanical longitudinal wave that propagates through a medium and can be heard.
transverse waveA wave in which the oscillations of the electric and magnetic fields are perpendicular to the direction of propagation.
waveA continuous, periodic disturbance that transfers energy between two locations without transferring matter.
wave pulseA single disturbance that transfers energy without transferring matter between two locations.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.

14.2 Periodic Waves

TermDefinition
amplitudeThe maximum displacement of a wave from its equilibrium position.
equilibriumThe position or state where a wave has zero displacement.
frequencyThe number of complete wave cycles that pass a point per unit time.
periodThe time required for one complete oscillation or cycle of a wave.
periodic waveA wave that repeats its pattern at regular intervals in space and time.
pitchThe perceived quality of a sound that is related to the frequency of the sound wave.
sinusoidal waveA wave whose displacement can be described by a sine or cosine function.
wave speedThe velocity at which a wave propagates through a medium.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.

14.3 Boundary Behavior of Waves and Polarization

TermDefinition
boundaryThe interface between two different media where wave interaction occurs.
frequencyThe number of complete wave cycles that pass a point per unit time.
intensityA measure of the average power transferred by a wave per unit area over one period.
longitudinal waveA wave in which particles oscillate parallel to the direction of wave propagation.
mediumA material or substance through which a wave travels.
polarizationThe process by which charges within a neutral system become separated, with positive charges shifting in one direction and negative charges in another.
powerThe rate at which energy is transferred, converted, or dissipated in an electric circuit, measured in watts.
reflected waveA wave that bounces back from a boundary between two media.
transmitted waveA wave that passes through a boundary and continues traveling into a new medium.
transverse waveA wave in which the oscillations of the electric and magnetic fields are perpendicular to the direction of propagation.
wave inversionA phase reversal of a reflected wave that occurs when the wave travels into a medium where the wave speed decreases.

14.4 Electromagnetic Waves

TermDefinition
blueA visible electromagnetic wave with a wavelength between green and violet.
electric fieldA vector quantity that represents the electric force per unit charge exerted at a given point in space, originating from charged objects.
electromagnetic radiationA collective term for all electromagnetic waves across the entire spectrum.
electromagnetic spectrumThe range of all types of electromagnetic waves ordered by wavelength, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
electromagnetic waveA wave consisting of oscillating electric and magnetic fields that are mutually perpendicular and can propagate without requiring a medium.
gamma raysElectromagnetic waves with the shortest wavelengths in the electromagnetic spectrum, measured in picometers.
greenA visible electromagnetic wave with a wavelength between yellow and blue.
infraredElectromagnetic waves with wavelengths shorter than microwaves but longer than visible light.
magnetic fieldA vector field that exerts a force on moving electric charges, electric currents, and magnetic materials.
microwavesElectromagnetic waves with wavelengths shorter than radio waves but longer than infrared radiation.
orangeA visible electromagnetic wave with a wavelength between red and yellow.
plane waveAn electromagnetic wave characterized by planar wave fronts.
propagationThe process by which electromagnetic waves travel through space without requiring a medium.
radio wavesElectromagnetic waves with the longest wavelengths in the electromagnetic spectrum, measured in kilometers.
redThe visible electromagnetic wave with the longest wavelength in the visible spectrum.
transverse waveA wave in which the oscillations of the electric and magnetic fields are perpendicular to the direction of propagation.
ultravioletElectromagnetic waves with wavelengths shorter than visible light but longer than X-rays.
violetThe visible electromagnetic wave with the shortest wavelength in the visible spectrum.
visible lightElectromagnetic waves with wavelengths that can be detected by the human eye, ranging from red to violet.
wave frontA surface of constant phase in a plane wave, perpendicular to the direction of propagation.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.
X-raysElectromagnetic waves with wavelengths shorter than ultraviolet radiation but longer than gamma rays.
yellowA visible electromagnetic wave with a wavelength between orange and green.

14.5 The Doppler Effect

TermDefinition
Doppler effectThe change in observed frequency of a wave due to relative motion between the source and observer.
observed frequencyThe frequency of a wave as measured by an observer, which may differ from the rest frequency due to relative motion.
relative velocityThe velocity of the wave source with respect to the observer.
rest frequencyThe frequency of a wave emitted by a source at rest relative to the observer.
wave sourceAn object or system that emits waves.

14.6 Wave Interference and Standing Waves

TermDefinition
amplitudeThe maximum displacement of a wave from its equilibrium position.
amplitude variationsPeriodic changes in the amplitude of a resultant wave when two or more traveling wave pulses or waves interact.
antinodeA point on a standing wave where the amplitude is always at maximum.
beat frequencyThe difference between the frequencies of two waves, calculated as |f₁ - f₂|, which determines the rate of amplitude variations.
beatsPeriodic amplitude variations that arise from the addition of two waves with slightly different frequencies.
constructive interferenceThe superposition of waves that results in a wave of greater amplitude, occurring when wavefronts are in phase.
destructive interferenceThe superposition of waves that results in a wave of reduced amplitude, occurring when wavefronts are out of phase.
fundamentalThe standing wave with the longest possible wavelength, also called the first harmonic.
harmonicA standing wave pattern characterized by a specific wavelength, numbered according to its rank from longest to shortest wavelength.
in phaseA condition where two waves have displacements in the same direction at the same location.
interferenceThe phenomenon where the wave nature of light is important and cannot be neglected, involving the superposition of light waves.
nodeA point on a standing wave where the amplitude is always zero.
odd harmonicsHarmonic patterns that can be established in a standing wave with a node at one end and an antinode at the other end.
out of phaseA condition where two waves have displacements in opposite directions at the same location.
second harmonicThe standing wave with the second-longest possible wavelength.
standing waveA wave pattern that results from interference between two waves traveling in opposite directions within a confined region, characterized by fixed points of zero and maximum amplitude.
superpositionThe principle that when two or more waves overlap, the resulting displacement is determined by adding the individual displacements.
third harmonicThe standing wave with the third-longest possible wavelength.
wave interferenceThe interaction of two or more wave pulses or waves that overlap and travel through each other.
wave pulsesIndividual disturbances that travel through a medium, characterized by a single peak or trough.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.

14.7 Diffraction

TermDefinition
central bright fringeThe brightest band at the center of a single-slit diffraction pattern, resulting from constructive interference.
constructive interferenceThe superposition of waves that results in a wave of greater amplitude, occurring when wavefronts are in phase.
destructive interferenceThe superposition of waves that results in a wave of reduced amplitude, occurring when wavefronts are out of phase.
diffractionThe spreading of a wave around the edges of an obstacle or through an opening.
diffraction patternThe pattern of light and dark bands produced when a wave passes through an opening, resulting from interference of multiple wavefronts.
interference patternThe observable pattern created by the superposition of multiple waves, resulting in regions of constructive and destructive interference.
monochromatic lightLight of a single wavelength or frequency.
path length differenceThe difference in distances traveled by two wavefronts, denoted as ΔD, which determines the type of interference between them.
single-slit diffractionThe diffraction pattern produced when a wave passes through a single narrow opening.
small angle approximationA mathematical approximation used when the angle θ is less than 10°, allowing simplified relationships between diffraction parameters.
wavefrontA surface of constant phase in a propagating wave, perpendicular to the direction of wave propagation.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.

14.8 Double-Slit Interference and Diffraction Gratings

TermDefinition
center maximumThe central bright fringe in a diffraction pattern, where all wavelengths of white light interfere constructively and appear white.
central bright fringeThe brightest band at the center of a single-slit diffraction pattern, resulting from constructive interference.
constructive interferenceThe superposition of waves that results in a wave of greater amplitude, occurring when wavefronts are in phase.
destructive interferenceThe superposition of waves that results in a wave of reduced amplitude, occurring when wavefronts are out of phase.
diffraction gratingAn optical device consisting of many evenly spaced parallel slits or openings that produce an interference pattern by superimposing numerous diffraction patterns.
diffraction patternThe pattern of light and dark bands produced when a wave passes through an opening, resulting from interference of multiple wavefronts.
dispersionThe separation of white light into its component wavelengths or colors based on their different angles of diffraction.
higher-order maximaBright fringes in a diffraction pattern at positions beyond the central maximum, corresponding to m = 1, 2, 3, and so on.
monochromatic lightLight of a single wavelength or frequency.
order of maximum brightnessThe integer m that designates the position of bright fringes in an interference pattern, where m = 0 for the central maximum, m = 1 for the first-order maximum, and so on.
path length differenceThe difference in distances traveled by two wavefronts, denoted as ΔD, which determines the type of interference between them.
slit separationThe distance between two adjacent slits, represented by the symbol d.
small angle approximationA mathematical approximation used when the angle θ is less than 10°, allowing simplified relationships between diffraction parameters.
wave diffractionThe bending and spreading of a wave as it passes through an opening or around an obstacle.
wave interferenceThe interaction of two or more wave pulses or waves that overlap and travel through each other.
wavefrontA surface of constant phase in a propagating wave, perpendicular to the direction of wave propagation.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.
white lightLight composed of all visible wavelengths combined, appearing colorless.
Young's double-slit experimentAn experiment demonstrating wave properties of particles through the observation of interference patterns.

14.9 Thin Film Interference

TermDefinition
absorbedLight that is taken in by a medium and converted to other forms of energy rather than being reflected or transmitted.
antireflection coatingA thin layer applied to a surface that uses destructive interference to eliminate reflected light by controlling thickness and index of refraction.
constructive interferenceThe superposition of waves that results in a wave of greater amplitude, occurring when wavefronts are in phase.
destructive interferenceThe superposition of waves that results in a wave of reduced amplitude, occurring when wavefronts are out of phase.
index of refractionA measure of how much a medium slows down light compared to its speed in vacuum, determining the degree of bending and reflection of light at interfaces.
normal incidenceLight striking a surface at a perpendicular angle (90 degrees) to the surface.
oil filmsA practical example of thin-film interference where spectrum colors are observed due to variations in film thickness.
phase changeA shift in the phase of a light wave upon reflection, which can be 180 degrees or zero degrees depending on the relative indices of refraction of the materials.
reflected rayA ray of light that bounces off a surface after reflection.
refractedThe bending of light as it passes from one medium to another with a different index of refraction.
soap bubblesA practical example of thin-film interference where color variations result from differences in film thickness.
thin filmA medium whose thickness is comparable to the wavelength of light, causing interference effects when light interacts with it.
thin-film interferenceThe wave interference pattern that occurs when light reflects from the two surfaces of a thin film, resulting in constructive or destructive interference.
transmittedLight that passes through a medium rather than being reflected or absorbed.
wave interferenceThe interaction of two or more wave pulses or waves that overlap and travel through each other.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.

📚Unit 15 – Modern Physics

15.1 Quantum Theory and Wave-Particle Duality

TermDefinition
atomic spectraThe characteristic pattern of discrete wavelengths of light emitted or absorbed by atoms, which quantum theory explains.
blackbody radiationElectromagnetic radiation emitted by an idealized object that absorbs all incident radiation, explained by quantum theory.
de Broglie wavelengthThe wavelength associated with a particle, calculated as λ = h/p, which increases as the particle's momentum decreases.
particle-like behaviorProperties of matter or energy that behave as discrete, localized objects with definite position and momentum, characteristic of particles.
photoelectric effectThe emission of electrons from a material when electromagnetic radiation is incident upon it.
photonA discrete, quantized packet of electromagnetic energy that make up light, which is massless and electrically neutral, with energy proportional to its frequency.
quantizedRestricted to discrete, specific values rather than continuous values, as applied to energy and momentum in bound quantum systems.
quantum theoryThe branch of physics that describes the behavior of matter and energy at atomic and subatomic scales, explaining phenomena that classical mechanics cannot.
wave-like behaviorProperties of matter or energy that exhibit characteristics of waves, such as interference and diffraction patterns.
Young's double-slit experimentAn experiment demonstrating wave properties of particles through the observation of interference patterns.

15.2 The Bohr Model of Atomic Structure

TermDefinition
atomThe smallest unit of matter that retains the properties of an element, consisting of a nucleus surrounded by electrons.
atomic elementA pure substance consisting of atoms with the same unique number of protons.
Bohr modelA historical model of atomic structure in which electrons move in circular orbits around the nucleus at specific energy levels determined by classical physics.
circular orbitIn the Bohr model, the path an electron follows around the nucleus, determined by the electron's charge, mass, and the electric force between the electron and nucleus.
de Broglie wavelengthThe wavelength associated with a particle, calculated as λ = h/p, which increases as the particle's momentum decreases.
discrete energy statesSpecific, quantized energy levels that an electron can occupy in an atom, as described by the Bohr model.
electric forceThe force exerted on a charged object by an electric field.
electronNegatively charged particles that serve as the primary charge carriers in most common electrical circuits.
ionAn atom with a nonzero net electric charge due to the loss or gain of electrons.
isotopeAn atom of an element with a specific number of neutrons and protons that distinguishes it from other atoms of the same element.
neutronA neutrally charged subatomic particle found in the nucleus of an atom.
nuclear notationA symbolic representation showing the number of protons and neutrons in an atom's nucleus.
nucleusThe small, positively charged central part of an atom containing protons and neutrons.
protonA positively charged subatomic particle found in the nucleus of an atom.
standing wave modelA model of electrons in atoms where the electron orbit's circumference must be an integer multiple of the electron's de Broglie wavelength, accounting for allowed energy states.

15.3 Emission and Absorption Spectra

TermDefinition
absorption spectrumThe pattern of specific frequencies of light absorbed by an element when electrons transition to higher energy states.
atomThe smallest unit of matter that retains the properties of an element, consisting of a nucleus surrounded by electrons.
binding energyThe energy required to remove an electron from an atom and cause ionization.
electronNegatively charged particles that serve as the primary charge carriers in most common electrical circuits.
emission spectrumThe pattern of specific frequencies of light emitted by an element when electrons transition to lower energy states.
energy level diagramA visual representation showing the allowed energy states of an atom and transitions between them.
energy stateA specific energy level that an electron can occupy in an atom.
excited stateAn energy state of an atom higher than the ground state, which an electron occupies after absorbing energy.
frequencyThe number of complete wave cycles that pass a point per unit time.
ground stateThe lowest energy level of an atom, where an electron requires the most energy to be removed.
interaction energyThe energy associated with the interaction between an electron and the nucleus in an atom.
ionizationThe process of removing an electron from an atom, resulting in a charged ion.
nucleusThe small, positively charged central part of an atom containing protons and neutrons.
photonA discrete, quantized packet of electromagnetic energy that make up light, which is massless and electrically neutral, with energy proportional to its frequency.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.

15.4 Blackbody Radiation

TermDefinition
blackbodyAn idealized object that absorbs all electromagnetic radiation incident upon it and emits radiation based solely on its temperature.
continuous spectrumA spectrum of electromagnetic radiation with all wavelengths present, emitted by a blackbody and dependent only on temperature.
electromagnetic radiationA collective term for all electromagnetic waves across the entire spectrum.
intensity per unit wavelengthThe amount of electromagnetic radiation energy emitted at each wavelength, used to characterize a blackbody's spectrum.
internal thermal energyThe total kinetic and potential energy of particles within an object due to its temperature.
peak wavelengthThe wavelength at which a blackbody emits the maximum intensity of radiation per unit wavelength.
Planck's lawA fundamental law describing the spectral distribution of electromagnetic radiation emitted by a blackbody, based on the quantization of light energy.
powerThe rate at which energy is transferred, converted, or dissipated in an electric circuit, measured in watts.
quantized energyEnergy that exists in discrete packets or quanta rather than continuous amounts.
Stefan-Boltzmann lawA law stating that the total power radiated by a blackbody is proportional to its surface area and the fourth power of its absolute temperature.
thermal equilibriumA state in which an object maintains a constant temperature and emits energy at the same rate it absorbs energy.
Wien's lawA law stating that the peak wavelength of radiation emitted by a blackbody is inversely proportional to its absolute temperature.

15.5 The Photoelectric Effect

TermDefinition
electromagnetic radiationA collective term for all electromagnetic waves across the entire spectrum.
kinetic energyThe energy of motion possessed by an object due to its velocity.
monochromatic lightLight of a single wavelength or frequency.
photoelectric effectThe emission of electrons from a material when electromagnetic radiation is incident upon it.
photonA discrete, quantized packet of electromagnetic energy that make up light, which is massless and electrically neutral, with energy proportional to its frequency.
threshold frequencyThe minimum frequency of incident light required to cause electron emission from a material via the photoelectric effect.
work functionThe minimum energy required to emit an electron from atoms in a material, represented by the symbol φ.

15.6 Compton Scattering

TermDefinition
Compton effectThe phenomenon in which a photon emerges from an interaction with an electron with lower energy and longer wavelength than the incoming photon.
Compton scatteringAn interaction between a photon and a free electron in which the photon transfers energy and momentum to the electron, resulting in a photon with lower energy and longer wavelength.
conservation of energyThe principle that the total energy in an isolated system remains constant, with energy transforming between different forms but not being created or destroyed.
conservation of momentumA principle stating that the total momentum of an isolated system remains constant in the absence of external forces.
energyThe capacity to do work; in Compton scattering, energy is transferred from the photon to the electron.
free electronAn electron that is not bound to an atom and can interact with a photon in Compton scattering.
frequencyThe number of complete wave cycles that pass a point per unit time.
momentumThe product of mass and velocity; in Compton scattering, momentum is transferred from the photon to the electron.
photonA discrete, quantized packet of electromagnetic energy that make up light, which is massless and electrically neutral, with energy proportional to its frequency.
wavelengthThe distance between consecutive points of the same phase in a wave, typically denoted by λ.

15.7 Fission, Fusion, and Nuclear Decay

TermDefinition
binding energyThe energy required to remove an electron from an atom and cause ionization.
conservation of energyThe principle that the total energy in an isolated system remains constant, with energy transforming between different forms but not being created or destroyed.
conservation of momentumA principle stating that the total momentum of an isolated system remains constant in the absence of external forces.
decay constantA parameter (λ) that characterizes the rate of radioactive decay and can be related to half-life through the equation λ = ln(2)/t₁/₂.
energy-mass equivalenceThe principle that mass and energy are interchangeable, expressed by the equation E=mc².
exponential decayA mathematical model describing how the number of radioactive nuclei decreases as a function of time, following the equation N = N₀e^(-λt).
half-lifeThe time it takes for half of the initial number of radioactive nuclei in a sample to spontaneously decay.
law of conservation of nucleon numberA principle stating that the total number of nucleons (protons and neutrons) remains constant in nuclear reactions.
neutronA neutrally charged subatomic particle found in the nucleus of an atom.
nuclear fissionThe process by which the nucleus of an atom splits into two or more smaller nuclei, often releasing energy.
nuclear fusionThe process by which two or more smaller nuclei combine to form a larger nucleus, often releasing energy.
nucleonsThe subatomic particles that make up the nucleus, consisting of protons and neutrons.
protonA positively charged subatomic particle found in the nucleus of an atom.
radioactive decayThe spontaneous transformation of a nucleus into one or more different nuclei, characterized by an exponential decrease in the number of radioactive nuclei over time.
radioactive nucleiUnstable nuclei that spontaneously transform into different nuclei through radioactive decay.
strong forceThe fundamental force that acts between nucleons at nuclear scales and is responsible for holding the nucleus together.

15.8 Types of Radioactive Decay

TermDefinition
alpha decayA radioactive decay process in which a nucleus ejects an alpha particle.
alpha particleA subatomic particle consisting of two neutrons and two protons, emitted during alpha decay; also called a helium nucleus.
antineutrinoThe antimatter counterpart of a neutrino, with no electrical charge and negligible mass.
beta-minus decayA radioactive decay process in which a neutron converts to a proton by emitting an electron and an antineutrino.
beta-plus decayA radioactive decay process in which a proton converts to a neutron by emitting a positron and a neutrino.
gamma decayA radioactive decay process in which an excited nucleus emits a photon to reach a lower energy state, typically following alpha or beta decay.
lepton numberThe number of electrons and neutrinos in a system; conserved in all nuclear decay processes.
neutrinoA subatomic particle with no electrical charge and negligible mass that interacts with matter only through the weak force and gravity.
nucleon numberThe total number of neutrons and protons in a nucleus; conserved in all nuclear decay processes.
positronA subatomic particle with the same mass as an electron but with opposite electric charge; also called an antielectron.
radioactive decayThe spontaneous transformation of a nucleus into one or more different nuclei, characterized by an exponential decrease in the number of radioactive nuclei over time.

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