IB Physics Terminology

This glossary follows the chapter structure of the IB Physics Guide for first assessment in 2025. It includes core syllabus terminology and additional terms needed to understand formal IB Physics teaching materials. The definitions are written for the IB course context while preserving physical and mathematical accuracy.

Pronunciation conventions

• UK pronunciations use broad phonemic transcription based on General British.
• US pronunciations use broad phonemic transcription based on General American.
• Each entry gives one recommended pronunciation. Some terms also have other accepted regional or individual variants.
• Multi-word terms are transcribed transparently for vocabulary learning. Stress, weak forms and connected speech may vary in complete sentences.
• Slashes indicate broad phonemic transcription. Primary stress is normally omitted for monosyllabic words.

Label	Meaning
UK	British English pronunciation
US	American English pronunciation

A.1 Kinematics

Term	Pronunciation	Definition
kinematics	UK: /ˌkɪnɪˈmætɪks/ US: /ˌkɪnəˈmætɪks/	The branch of mechanics that describes motion without referring to the forces that cause it.
reference point	UK: /ˈrefərəns pɔɪnt/ US: /ˈrefərəns pɔɪnt/	A chosen fixed point relative to which position is measured.
reference frame	UK: /ˈrefərəns freɪm/ US: /ˈrefərəns freɪm/	A coordinate system together with synchronized clocks used to assign positions and times to events.
position	UK: /pəˈzɪʃən/ US: /pəˈzɪʃən/	The location of an object relative to a chosen origin.
distance travelled	UK: /ˈdɪstəns ˈtrævəld/ US: /ˈdɪstəns ˈtrævəld/	The total length of the path followed by an object.
displacement	UK: /dɪˈspleɪsmənt/ US: /dɪˈspleɪsmənt/	The vector change in position from the initial point to the final point.
scalar quantity	UK: /ˈskeɪlə ˈkwɒntɪti/ US: /ˈskeɪlər ˈkwɑːntəti/	A physical quantity described by magnitude only.
vector quantity	UK: /ˈvektə ˈkwɒntɪti/ US: /ˈvektɚ ˈkwɑːntəti/	A physical quantity described by both magnitude and direction.
speed	UK: /spiːd/ US: /spiːd/	The scalar rate at which distance is travelled; equivalently, the magnitude of velocity.
velocity	UK: /vəˈlɒsɪti/ US: /vəˈlɑːsəti/	The vector rate of change of position.
average speed	UK: /ˈævrɪdʒ spiːd/ US: /ˈævərɪdʒ spiːd/	Total distance travelled divided by total elapsed time.
average velocity	UK: /ˈævrɪdʒ vəˈlɒsɪti/ US: /ˈævərɪdʒ vəˈlɑːsəti/	Total displacement divided by total elapsed time.
instantaneous velocity	UK: /ˌɪnstɑːnˈteɪniəs vəˈlɒsɪti/ US: /ˌɪnstənˈtæniəs vəˈlɑːsəti/	The velocity of an object at a particular instant.
acceleration	UK: /əkˌseləˈreɪʃən/ US: /əkˌseləˈreɪʃən/	The vector rate of change of velocity.
uniform acceleration	UK: /ˈjuːnɪˌfɔːm əkˌseləˈreɪʃən/ US: /ˈjuːnəˌfɔːrm əkˌseləˈreɪʃən/	Motion with constant acceleration as a vector.
free fall	UK: /friː fɔːl/ US: /friː fɔːl/	Motion under the influence of gravity alone.
projectile motion	UK: /prəˈdʒektaɪl ˈməʊʃən/ US: /prəˈdʒektəl ˈmoʊʃən/	Motion after launch under gravity alone, modelled with a uniform gravitational field and negligible air resistance.
trajectory	UK: /trəˈdʒektəri/ US: /trəˈdʒektɚi/	The path followed by a moving object.
range	UK: /reɪndʒ/ US: /reɪndʒ/	The horizontal displacement of a projectile from launch to landing.
time of flight	UK: /taɪm əv flaɪt/ US: /taɪm əv flaɪt/	The total time for which a projectile remains in motion before landing.
gradient	UK: /ˈɡreɪdɪənt/ US: /ˈɡreɪdiənt/	The change in the vertical-axis quantity per unit change in the horizontal-axis quantity.
area under a graph	UK: /ˈeəriə ˈʌndə ə ɡrɑːf/ US: /ˈeriə ˈʌndɚ ə ɡræf/	The signed geometrical area between a graph and its horizontal axis.

A.2 Forces and momentum

Term	Pronunciation	Definition
force	UK: /fɔːs/ US: /fɔːrs/	A push or pull arising from an interaction; the resultant force on a body equals its rate of change of momentum.
resultant force	UK: /rɪˈzʌltənt fɔːs/ US: /rɪˈzʌltənt fɔːrs/	The vector sum of all forces acting on an object.
free-body diagram	UK: /friː ˈbɒdi ˈdaɪəɡræm/ US: /friː ˈbɑːdi ˈdaɪəɡræm/	A diagram showing all external forces acting on one chosen body.
inertia	UK: /ɪˈnɜːʃə/ US: /ˌɪˈnɝːʃə/	The property of a body by which it resists a change in velocity; mass is its quantitative measure.
Newton’s first law	UK: /ˈnjuːtənz fɜːst lɔː/ US: /ˈnuːtənz fɝːst lɔː/	An object remains at rest or in uniform straight-line motion unless acted on by a resultant external force.
Newton’s second law	UK: /ˈnjuːtənz ˈsekənd lɔː/ US: /ˈnuːtənz ˈsekənd lɔː/	The resultant force equals the rate of change of momentum; for constant mass, it equals mass times acceleration.
Newton’s third law	UK: /ˈnjuːtənz θɜːd lɔː/ US: /ˈnuːtənz θɝːd lɔː/	When two bodies interact, they exert equal and opposite forces on each other.
mass	UK: /mæs/ US: /mæs/	A scalar measure of a body’s inertia.
weight	UK: /weɪt/ US: /weɪt/	The gravitational force acting on an object.
normal contact force	UK: /ˈnɔːməl kənˈtækt fɔːs/ US: /ˈnɔːrməl ˈkɑːnˌtækt fɔːrs/	The component of a contact force perpendicular to the contact surface.
tension	UK: /ˈtenʃən/ US: /ˈtenʃən/	A pulling force transmitted through a stretched string, rope or cable.
friction	UK: /ˈfrɪkʃən/ US: /ˈfrɪkʃən/	A tangential contact force that opposes relative sliding or the tendency to slide between surfaces.
static friction	UK: /ˈstætɪk ˈfrɪkʃən/ US: /ˈstætɪk ˈfrɪkʃən/	Friction between surfaces that are not sliding relative to each other.
limiting friction	UK: /ˈlɪmɪtɪŋ ˈfrɪkʃən/ US: /ˈlɪmətɪŋ ˈfrɪkʃən/	The maximum possible static friction immediately before slipping begins.
dynamic friction	UK: /daɪˈnæmɪk ˈfrɪkʃən/ US: /daɪˈnæmɪk ˈfrɪkʃən/	Friction between surfaces that are sliding relative to each other.
coefficient of friction	UK: /ˌkəʊɪˈfɪʃənt əv ˈfrɪkʃən/ US: /ˌkoʊəˈfɪʃənt əv ˈfrɪkʃən/	The dimensionless constant relating frictional force to normal contact force in the stated friction model.
drag force	UK: /dræɡ fɔːs/ US: /dræɡ fɔːrs/	A resistive force exerted by a fluid on an object moving through it.
buoyant force	UK: /ˈbɔɪənt fɔːs/ US: /ˈbɔɪənt fɔːrs/	The resultant force exerted by a fluid on an immersed or partially immersed body, arising from pressure differences.
terminal speed	UK: /ˈtɜːmɪnəl spiːd/ US: /ˈtɝːmənəl spiːd/	The constant speed reached when the resultant force is zero and hence acceleration is zero.
momentum	UK: /məˈmentəm/ US: /moʊˈmentəm/	The vector product of mass and velocity.
impulse	UK: /ˈɪmpəls/ US: /ˈɪmpəls/	The time integral of force; the resultant impulse on a body equals its change in momentum.
conservation of momentum	UK: /ˌkɒnsəˈveɪʃən əv məˈmentəm/ US: /ˌkɑːnsɚˈveɪʃən əv moʊˈmentəm/	The total momentum of a system remains constant when the resultant external impulse is zero.
elastic collision	UK: /ɪˈlæstɪk kəˈlɪʒən/ US: /ɪˈlæstɪk kəˈlɪʒən/	A collision in an isolated system in which total momentum and total kinetic energy are conserved.
inelastic collision	UK: /ˌɪnɪˈlæstɪk kəˈlɪʒən/ US: /ˌɪnəˈlæstɪk kəˈlɪʒən/	A collision in which total kinetic energy is not conserved; total momentum is conserved if the external impulse is zero.
perfectly inelastic collision	UK: /ˈpɜːfɪktli ˌɪnɪˈlæstɪk kəˈlɪʒən/ US: /ˈpɝːfɪktli ˌɪnəˈlæstɪk kəˈlɪʒən/	A collision after which the objects move together with a common velocity.
explosion	UK: /ɪkˈspləʊʒən/ US: /ɪkˈsploʊʒən/	An internal process that separates parts of a system and redistributes energy and momentum.
uniform circular motion	UK: /ˈjuːnɪˌfɔːm ˈsɜːkjʊlə ˈməʊʃən/ US: /ˈjuːnəˌfɔːrm ˈsɝːkjələr ˈmoʊʃən/	Motion at constant speed along a circular path.
centripetal acceleration	UK: /ˌsentrɪˈpiːtəl əkˌseləˈreɪʃən/ US: /senˈtrɪpətəl əkˌseləˈreɪʃən/	Acceleration directed towards the centre of a circular path.
centripetal force	UK: /ˌsentrɪˈpiːtəl fɔːs/ US: /senˈtrɪpətəl fɔːrs/	The resultant radial force that produces centripetal acceleration.
angular speed	UK: /ˈænɡjʊlə spiːd/ US: /ˈæŋɡjəlɚ spiːd/	The rate of change of angular displacement.
period	UK: /ˈpɪərɪəd/ US: /ˈpɪriəd/	The time taken to complete one full cycle or revolution.

A.3 Work, energy and power

Term	Pronunciation	Definition
work	UK: /wɜːk/ US: /wɝːk/	Energy transferred mechanically when a force acts through a displacement.
work done	UK: /wɜːk dən/ US: /wɝːk dʌn/	For a constant force, the scalar product of force and displacement; more generally, the integral of force along the path.
energy	UK: /ˈenədʒi/ US: /ˈenɚdʒi/	A conserved scalar property of a system that can be transferred between systems or transformed between forms.
kinetic energy	UK: /kɪˈnetɪk ˈenədʒi/ US: /kɪˈnetɪk ˈenɚdʒi/	Energy associated with an object’s motion.
gravitational potential energy	UK: /ˌɡrævɪˈteɪʃənəl pəˈtenʃəl ˈenədʒi/ US: /ˌɡrævɪˈteɪʃənəl pəˈtenʃəl ˈenɚdʒi/	Energy associated with the configuration of masses in a gravitational field.
elastic potential energy	UK: /ɪˈlæstɪk pəˈtenʃəl ˈenədʒi/ US: /ɪˈlæstɪk pəˈtenʃəl ˈenɚdʒi/	Energy stored when an elastic object is stretched or compressed.
mechanical energy	UK: /mɪˈkænɪkəl ˈenədʒi/ US: /məˈkænɪkəl ˈenɚdʒi/	The sum of the kinetic energies and the relevant potential energies of a mechanical system.
conservation of energy	UK: /ˌkɒnsəˈveɪʃən əv ˈenədʒi/ US: /ˌkɑːnsɚˈveɪʃən əv ˈenɚdʒi/	The total energy of an isolated system remains constant, although energy may be transferred or transformed.
work-energy theorem	UK: /wɜːk ˈenədʒi ˈθɪərəm/ US: /wɝːk ˈenɚdʒi ˈθɪrəm/	The resultant work done on an object equals its change in kinetic energy.
power	UK: /ˈpaʊə/ US: /ˈpaʊɚ/	The rate at which work is done or energy is transferred.
efficiency	UK: /ɪˈfɪʃənsi/ US: /ɪˈfɪʃənsi/	The ratio of useful energy output or power output to total input.
dissipation	UK: /ˌdɪsɪˈpeɪʃən/ US: /ˌdɪsɪˈpeɪʃən/	The transfer of energy from organized macroscopic forms into internal energy distributed among many microscopic degrees of freedom.
system	UK: /ˈsɪstəm/ US: /ˈsɪstəm/	The object or collection of objects selected for analysis.
energy transfer	UK: /ˈenədʒi ˈtrænsfɜː/ US: /ˈenɚdʒi ˈtrænsfɝː/	The movement of energy from one system or part of a system to another, for example by work, heating or radiation.
conservative force	UK: /kənˈsɜːvətɪv fɔːs/ US: /kənˈsɝːvətɪv fɔːrs/	A force whose work between two positions is independent of path; equivalently, its work around any closed path is zero.

A.4 Rigid body mechanics

Term	Pronunciation	Definition
rigid body	UK: /ˈrɪdʒɪd ˈbɒdi/ US: /ˈrɪdʒəd ˈbɑːdi/	An idealized body whose shape and dimensions do not change.
translational motion	UK: /trænˈsleɪʃənəl ˈməʊʃən/ US: /trænzˈleɪʃənəl ˈmoʊʃən/	Motion in which every point of a body has the same displacement.
rotational motion	UK: /rəʊˈteɪʃənəl ˈməʊʃən/ US: /roʊˈteɪʃənəl ˈmoʊʃən/	Motion of a body about an axis.
axis of rotation	UK: /ˈæksɪs əv rəʊˈteɪʃən/ US: /ˈæksəs əv roʊˈteɪʃən/	The line about which a body rotates.
angular displacement	UK: /ˈænɡjʊlə dɪˈspleɪsmənt/ US: /ˈæŋɡjəlɚ dɪˈspleɪsmənt/	The angle through which a body rotates, with a specified sense.
angular velocity	UK: /ˈænɡjʊlə vəˈlɒsɪti/ US: /ˈæŋɡjəlɚ vəˈlɑːsəti/	The vector rate of change of angular displacement, directed along the rotation axis by the right-hand rule.
angular acceleration	UK: /ˈænɡjʊlə əkˌseləˈreɪʃən/ US: /ˈæŋɡjəlɚ əkˌseləˈreɪʃən/	The rate of change of angular velocity.
torque	UK: /tɔːk/ US: /tɔːrk/	The vector turning effect of a force about a chosen point or axis.
moment arm	UK: /ˈməʊmənt ɑːm/ US: /ˈmoʊmənt ɑːrm/	The perpendicular distance from the axis to the line of action of a force.
line of action	UK: /laɪn əv ˈækʃən/ US: /laɪn əv ˈækʃən/	The infinite straight line along which a force acts.
centre of mass	UK: /ˈsentə əv mæs/ US: /ˈsentɚ əv mæs/	The mass-weighted mean position of a body or system; its translational motion follows the resultant external force.
translational equilibrium	UK: /trænˈsleɪʃənəl ˌiːkwɪˈlɪbrɪəm/ US: /trænzˈleɪʃənəl ˌiːkwəˈlɪbriəm/	A state in which the resultant force is zero.
rotational equilibrium	UK: /rəʊˈteɪʃənəl ˌiːkwɪˈlɪbrɪəm/ US: /roʊˈteɪʃənəl ˌiːkwəˈlɪbriəm/	A state in which the resultant torque is zero.
static equilibrium	UK: /ˈstætɪk ˌiːkwɪˈlɪbrɪəm/ US: /ˈstætɪk ˌiːkwəˈlɪbriəm/	A state in which a body is at rest and both the resultant force and resultant torque are zero.
moment of inertia	UK: /ˈməʊmənt əv ɪˈnɜːʃə/ US: /ˈmoʊmənt əv ˌɪˈnɝːʃə/	A scalar measure of how mass is distributed relative to a chosen rotation axis and hence of resistance to angular acceleration about that axis.
rotational kinetic energy	UK: /rəʊˈteɪʃənəl kɪˈnetɪk ˈenədʒi/ US: /roʊˈteɪʃənəl kɪˈnetɪk ˈenɚdʒi/	The kinetic energy associated with rotation.
angular momentum	UK: /ˈænɡjʊlə məˈmentəm/ US: /ˈæŋɡjəlɚ moʊˈmentəm/	A vector measure of rotational motion; for a rigid body about a fixed principal axis, its magnitude is $I\omega$.
conservation of angular momentum	UK: /ˌkɒnsəˈveɪʃən əv ˈænɡjʊlə məˈmentəm/ US: /ˌkɑːnsɚˈveɪʃən əv ˈæŋɡjəlɚ moʊˈmentəm/	Total angular momentum remains constant when resultant external torque is zero.
rolling without slipping	UK: /ˈrəʊlɪŋ wɪˈðaʊt ˈslɪpɪŋ/ US: /ˈroʊlɪŋ wɪˈθaʊt ˈslɪpɪŋ/	Combined translation and rotation with no relative motion at the contact point.
pure rolling	UK: /pjʊə ˈrəʊlɪŋ/ US: /pjʊr ˈroʊlɪŋ/	Another term for rolling without slipping.

A.5 Galilean and special relativity

Term	Pronunciation	Definition
event	UK: /ɪˈvent/ US: /ɪˈvent/	Something that occurs at one position and one instant.
reference frame	UK: /ˈrefərəns freɪm/ US: /ˈrefərəns freɪm/	A coordinate system together with synchronized clocks used to assign positions and times to events.
inertial reference frame	UK: /ɪˈnɜːʃəl ˈrefərəns freɪm/ US: /ˌɪˈnɝːʃəl ˈrefərəns freɪm/	A reference frame in which a free body has constant velocity and Newton’s first law holds.
rest frame	UK: /rest freɪm/ US: /rest freɪm/	A frame in which a specified object is at rest.
Galilean relativity	UK: /ˌɡælɪˈleɪən rɪləˈtɪvɪti/ US: /ˌɡælɪˈliːən ˌreləˈtɪvəti/	The principle that Newtonian mechanics has the same form in all inertial frames.
Galilean transformation	UK: /ˌɡælɪˈleɪən ˌtrænsfəˈmeɪʃən/ US: /ˌɡælɪˈliːən ˌtrænsfɚˈmeɪʃən/	The classical equations relating event coordinates in uniformly moving frames.
velocity addition	UK: /vəˈlɒsɪti əˈdɪʃən/ US: /vəˈlɑːsəti əˈdɪʃən/	A relation connecting the velocity of an object measured in different frames.
special relativity	UK: /ˈspeʃəl rɪləˈtɪvɪti/ US: /ˈspeʃəl ˌreləˈtɪvəti/	The theory based on the equivalence of inertial frames and the invariance of the speed of light in vacuum.
postulate	UK: /ˈpɒstʃələt/ US: /ˈpɑːstʃələt/	A fundamental assumption adopted as a basis of a theory.
speed of light	UK: /spiːd əv laɪt/ US: /spiːd əv laɪt/	The invariant speed of electromagnetic radiation in vacuum.
Lorentz transformation	UK: /ˈlɒrənts ˌtrænsfəˈmeɪʃən/ US: /ˈlɔːrents ˌtrænsfɚˈmeɪʃən/	The relativistic equations relating space and time coordinates in inertial frames.
Lorentz factor	UK: /ˈlɒrənts ˈfæktə/ US: /ˈlɔːrents ˈfæktɚ/	The factor that determines the size of relativistic effects at a given relative speed.
relativistic velocity addition	UK: /ˌrelətɪˈvɪstɪk vəˈlɒsɪti əˈdɪʃən/ US: /ˌrelətɪˈvɪstɪk vəˈlɑːsəti əˈdɪʃən/	The velocity transformation consistent with an invariant speed of light.
space-time interval	UK: /speɪs taɪm ˈɪntəvəl/ US: /speɪs taɪm ˈɪntɚvəl/	The Lorentz-invariant combination of the temporal and spatial separations between two events.
invariant quantity	UK: /ɪnˈveəriənt ˈkwɒntɪti/ US: /ˌɪnˈveriənt ˈkwɑːntəti/	A quantity that has the same value in all relevant reference frames.
proper time	UK: /ˈprɒpə taɪm/ US: /ˈprɑːpɚ taɪm/	The time interval between two events measured by a single clock present at both events.
proper length	UK: /ˈprɒpə leŋθ/ US: /ˈprɑːpɚ leŋkθ/	The length of an object measured simultaneously in the object’s rest frame.
time dilation	UK: /taɪm daɪˈleɪʃən/ US: /taɪm ˌdaɪˈleɪʃən/	The relation by which the time interval between two events is greater in a frame where they occur at different positions than the proper time.
length contraction	UK: /leŋθ kənˈtrækʃən/ US: /leŋkθ kənˈtrækʃən/	The measured length of an object parallel to relative motion is shorter than its proper length.
relativity of simultaneity	UK: /rɪləˈtɪvɪti əv ˌsɪməlˈteɪnɪti/ US: /ˌreləˈtɪvəti əv ˌsaɪməltəˈniːəti/	The dependence of simultaneity of separated events on the observer’s frame.
space-time diagram	UK: /speɪs taɪm ˈdaɪəɡræm/ US: /speɪs taɪm ˈdaɪəɡræm/	A diagram representing position and time coordinates of events.
world line	UK: /wɜːld laɪn/ US: /wɝːld laɪn/	The path of an object through space-time.
muon decay	UK: /ˈmjuːɒn dɪˈkeɪ/ US: /ˈmjuːɑːn dɪˈkeɪ/	The spontaneous transformation of a muon into lighter particles.
low-speed limit	UK: /ləʊ spiːd ˈlɪmɪt/ US: /loʊ spiːd ˈlɪmət/	The regime $v\ll c$ in which relativistic predictions approach the corresponding classical results.

B.1 Thermal energy transfers

Term	Pronunciation	Definition
particle model	UK: /ˈpɑːtɪkəl ˈmɒdəl/ US: /ˈpɑːrtəkəl ˈmɑːdəl/	A model that explains matter in terms of moving and interacting particles.
solid	UK: /ˈsɒlɪd/ US: /ˈsɑːləd/	A state of matter with fixed volume and shape under ordinary conditions.
liquid	UK: /ˈlɪkwɪd/ US: /ˈlɪkwəd/	A state of matter with fixed volume but no fixed shape.
gas	UK: /ɡæs/ US: /ɡæs/	A state of matter with neither fixed shape nor fixed volume.
density	UK: /ˈdensɪti/ US: /ˈdensəti/	Mass per unit volume.
temperature	UK: /ˈtemprətʃə/ US: /ˈtemprətʃɚ/	A thermodynamic state quantity that determines the direction of net thermal energy transfer; for an ideal gas it is proportional to mean translational kinetic energy.
Kelvin scale	UK: /ˈkelvɪn skeɪl/ US: /ˈkelvən skeɪl/	The absolute thermodynamic temperature scale, with zero kelvin at absolute zero.
Celsius scale	UK: /ˈselsiəs skeɪl/ US: /ˈselsiəs skeɪl/	A temperature scale whose degree has the same size as the kelvin and for which 0 °C corresponds to 273.15 K.
absolute zero	UK: /ˈæbsəˌluːt ˈzɪərəʊ/ US: /ˈæbsəˌluːt ˈzɪroʊ/	The zero of thermodynamic temperature, equal to 0 K or −273.15 °C.
internal energy	UK: /ɪnˈtɜːnəl ˈenədʒi/ US: /ˌɪnˈtɝːnəl ˈenɚdʒi/	The total microscopic kinetic and potential energy within a system, excluding its macroscopic kinetic and potential energies.
thermal equilibrium	UK: /ˈθɜːməl ˌiːkwɪˈlɪbrɪəm/ US: /ˈθɝːməl ˌiːkwəˈlɪbriəm/	A state in which systems in thermal contact have no net energy transfer between them by heating.
phase change	UK: /feɪz tʃeɪndʒ/ US: /feɪz tʃeɪndʒ/	A change of state occurring through a change in particle arrangement and energy.
melting	UK: /ˈmeltɪŋ/ US: /ˈmeltɪŋ/	The change from solid to liquid.
freezing	UK: /ˈfriːzɪŋ/ US: /ˈfriːzɪŋ/	The change from liquid to solid.
boiling	UK: /ˈbɔɪlɪŋ/ US: /ˈbɔɪlɪŋ/	Vaporization throughout a liquid at its boiling temperature.
evaporation	UK: /ɪˌvæpəˈreɪʃən/ US: /ɪˌvæpɚˈeɪʃən/	Vaporization from the surface of a liquid below or at its boiling point.
condensation	UK: /kɒndɪnˈseɪʃən/ US: /ˌkɑːndənˈseɪʃən/	The change from gas to liquid.
specific heat capacity	UK: /spɪˈsɪfɪk hiːt kəˈpæsɪti/ US: /spəˈsɪfɪk hiːt kəˈpæsəti/	The energy required per unit mass to raise a substance’s temperature by one kelvin, without a change of state.
specific latent heat	UK: /spɪˈsɪfɪk ˈleɪtənt hiːt/ US: /spəˈsɪfɪk ˈleɪtənt hiːt/	The energy transferred per unit mass during a specified change of state at constant temperature.
conduction	UK: /kənˈdəkʃən/ US: /kənˈdʌkʃən/	Thermal energy transfer through microscopic particle interactions, without bulk transport of matter.
convection	UK: /kənˈvekʃən/ US: /kənˈvekʃən/	Thermal energy transfer by the bulk motion of a fluid.
thermal radiation	UK: /ˈθɜːməl ˌreɪdɪˈeɪʃən/ US: /ˈθɝːməl ˌreɪdiˈeɪʃən/	Electromagnetic radiation emitted by matter because of its temperature, transferring energy without requiring a material medium.
thermal conductivity	UK: /ˈθɜːməl kɒndəkˈtɪvɪti/ US: /ˈθɝːməl ˌkɑːnˌdʌkˈtɪvəti/	A material property measuring its ability to conduct thermal energy.
black body	UK: /blæk ˈbɒdi/ US: /blæk ˈbɑːdi/	An ideal body that absorbs all incident electromagnetic radiation and, at a given temperature, emits the maximum possible thermal radiation.
luminosity	UK: /ˌluːmɪˈnɒsɪti/ US: /ˌluːməˈnɑːsəti/	The total power radiated by a body.
apparent brightness	UK: /əˈpærənt ˈbraɪtnəs/ US: /əˈperənt ˈbraɪtnəs/	The radiant power received per unit area from an astronomical source.
Stefan-Boltzmann law	UK: /ˈstefən ˈbɒltsmən lɔː/ US: /ˈstefən ˈboʊltsmən lɔː/	The law relating black-body luminosity to area and the fourth power of temperature.
Wien’s displacement law	UK: /viːnz dɪˈspleɪsmənt lɔː/ US: /viːnz dɪˈspleɪsmənt lɔː/	The law relating a black body’s peak wavelength to its temperature.

B.2 Greenhouse effect

Term	Pronunciation	Definition
greenhouse effect	UK: /ˈɡriːnˌhaʊs ɪˈfekt/ US: /ˈɡriːnˌhaʊs ɪˈfekt/	The warming of a planet’s surface and lower atmosphere because the atmosphere absorbs and re-emits outgoing infrared radiation.
natural greenhouse effect	UK: /ˈnætʃrəl ˈɡriːnˌhaʊs ɪˈfekt/ US: /ˈnætʃɚəl ˈɡriːnˌhaʊs ɪˈfekt/	The greenhouse warming that occurs naturally in a planetary atmosphere.
enhanced greenhouse effect	UK: /ɪnˈhɑːnst ˈɡriːnˌhaʊs ɪˈfekt/ US: /enˈhænst ˈɡriːnˌhaʊs ɪˈfekt/	Additional warming caused by increased greenhouse-gas concentrations.
greenhouse gas	UK: /ˈɡriːnˌhaʊs ɡæs/ US: /ˈɡriːnˌhaʊs ɡæs/	An atmospheric gas that absorbs and emits infrared radiation at relevant wavelengths.
carbon dioxide	UK: /ˈkɑːbən daɪˈɒkˌsaɪd/ US: /ˈkɑːrbən daɪˈɑːkˌsaɪd/	A greenhouse gas whose atmospheric concentration is increased by fossil-fuel combustion.
infrared radiation	UK: /ˌɪnfrəˈred ˌreɪdɪˈeɪʃən/ US: /ˌɪnfrɚˈed ˌreɪdiˈeɪʃən/	Electromagnetic radiation with wavelengths longer than visible light.
emissivity	UK: /ˌemɪˈsɪvəti/ US: /ˌemɪˈsɪvəti/	At a stated wavelength or over a stated spectrum, the ratio of a surface’s emitted radiative power to that of an ideal black body at the same temperature and area.
albedo	UK: /ælˈbiːdəʊ/ US: /ælˈbiːdoʊ/	The fraction of incident radiant power that a surface or body reflects.
radiative equilibrium	UK: /ˈreɪdiətɪv ˌiːkwɪˈlɪbrɪəm/ US: /ˈreɪdiətɪv ˌiːkwəˈlɪbriəm/	A state in which absorbed and emitted radiative powers are balanced.
energy balance	UK: /ˈenədʒi ˈbæləns/ US: /ˈenɚdʒi ˈbæləns/	An accounting of energy entering, leaving and being stored in a system.
absorption	UK: /əbˈzɔːpʃən/ US: /əbˈzɔːrpʃən/	The transfer of radiation energy into matter.
emission	UK: /ɪˈmɪʃən/ US: /ɪˈmɪʃən/	The release of electromagnetic radiation by matter.
re-emission	UK: /ˌriːɪˈmɪʃən/ US: /ˌriːɪˈmɪʃən/	The emission of energy after it has previously been absorbed.
radiative forcing	UK: /ˈreɪdiətɪv ˈfɔːsɪŋ/ US: /ˈreɪdiətɪv ˈfɔːrsɪŋ/	A change in the net radiative energy flux of a climate system.
climate feedback	UK: /ˈklaɪmɪt ˈfiːdˌbæk/ US: /ˈklaɪmət ˈfiːdˌbæk/	A process that amplifies or reduces an initial climate change.

B.3 Gas laws

Term	Pronunciation	Definition
pressure	UK: /ˈpreʃə/ US: /ˈpreʃɚ/	The normal force exerted per unit area.
ideal gas	UK: /aɪˈdɪəl ɡæs/ US: /aɪˈdiːl ɡæs/	A model gas of particles with negligible volume, no intermolecular forces except during collisions, and perfectly elastic collisions.
amount of substance	UK: /əˈmaʊnt əv ˈsəbstəns/ US: /əˈmaʊnt əv ˈsʌbstəns/	A base quantity proportional to the number of specified elementary entities in a sample, measured in moles.
mole	UK: /məʊl/ US: /moʊl/	The amount of substance containing exactly $6.02214076\times10^{23}$ specified elementary entities.
Avogadro constant	UK: /ˌævəˈɡɑːdrəʊ ˈkɒnstənt/ US: /ˌɑːvəˈɡɑːdroʊ ˈkɑːnstənt/	The exact number of specified elementary entities per mole, $6.02214076\times10^{23}\ \mathrm{mol^{-1}}$.
molar mass	UK: /ˈməʊlə mæs/ US: /ˈmoʊlər mæs/	The mass of a substance divided by its amount of substance.
absolute temperature	UK: /ˈæbsəˌluːt ˈtemprətʃə/ US: /ˈæbsəˌluːt ˈtemprətʃɚ/	Thermodynamic temperature measured from absolute zero.
equation of state	UK: /ɪˈkweɪʒən əv steɪt/ US: /ɪˈkweɪʒən əv steɪt/	A relation connecting pressure, volume, temperature and amount of gas.
ideal gas law	UK: /aɪˈdɪəl ɡæs lɔː/ US: /aɪˈdiːl ɡæs lɔː/	The equation relating pressure, volume, amount of substance and absolute temperature for an ideal gas.
Boyle’s law	UK: /bɔɪlz lɔː/ US: /bɔɪlz lɔː/	For fixed temperature and amount of gas, pressure is inversely proportional to volume.
Charles’s law	UK: /ˈtʃɑːlzɪz lɔː/ US: /ˈtʃɑːrlzɪz lɔː/	For fixed pressure and amount of gas, volume is proportional to absolute temperature.
pressure law	UK: /ˈpreʃə lɔː/ US: /ˈpreʃɚ lɔː/	For fixed volume and amount of gas, pressure is proportional to absolute temperature.
kinetic theory	UK: /kɪˈnetɪk ˈθɪəri/ US: /kɪˈnetɪk ˈθɪri/	A microscopic theory that explains the macroscopic behaviour of gases in terms of particle motion and collisions.
elastic collision	UK: /ɪˈlæstɪk kəˈlɪʒən/ US: /ɪˈlæstɪk kəˈlɪʒən/	A collision in an isolated system in which total momentum and total kinetic energy are conserved.
mean square speed	UK: /miːn skweə spiːd/ US: /miːn skwer spiːd/	The average of the squares of particle speeds in a gas.
root-mean-square speed	UK: /ruːt miːn skweə spiːd/ US: /ruːt miːn skwer spiːd/	The square root of the mean square speed.
molecular collision	UK: /məˈlekjʊlə kəˈlɪʒən/ US: /məˈlekjəlɚ kəˈlɪʒən/	An interaction in which gas particles exchange momentum and energy.
microscopic model	UK: /ˌmaɪkrəˈskɒpɪk ˈmɒdəl/ US: /ˌmaɪkrəˈskɑːpɪk ˈmɑːdəl/	A model describing macroscopic behaviour in terms of particles and their interactions.

B.4 Thermodynamics

Term	Pronunciation	Definition
thermodynamics	UK: /ˌθɜːməʊdaɪˈnæmɪks/ US: /ˌθɝːmoʊdaɪˈnæmɪks/	The study of energy transfer, heat, work and macroscopic state changes.
thermodynamic system	UK: /ˌθɜːməʊdaɪˈnæmɪk ˈsɪstəm/ US: /ˌθɝːmoʊdaɪˈnæmɪk ˈsɪstəm/	The matter or region selected for thermodynamic analysis.
surroundings	UK: /səˈraʊndɪŋz/ US: /sɚˈaʊndɪŋz/	Everything outside the chosen thermodynamic system.
boundary	UK: /ˈbaʊndri/ US: /ˈbaʊndɚi/	The real or imaginary surface separating a system from its surroundings.
state variable	UK: /steɪt ˈveərɪəbəl/ US: /steɪt ˈveriəbəl/	A macroscopic quantity determined by the equilibrium state of a system.
internal energy	UK: /ɪnˈtɜːnəl ˈenədʒi/ US: /ˌɪnˈtɝːnəl ˈenɚdʒi/	The total microscopic kinetic and potential energy within a system, excluding its macroscopic kinetic and potential energies.
heat	UK: /hiːt/ US: /hiːt/	Energy transferred between systems solely because of a temperature difference.
work	UK: /wɜːk/ US: /wɝːk/	Energy transferred mechanically when a force acts through a displacement.
first law of thermodynamics	UK: /fɜːst lɔː əv ˌθɜːməʊdaɪˈnæmɪks/ US: /fɝːst lɔː əv ˌθɝːmoʊdaɪˈnæmɪks/	Using the IB sign convention, $Q=\Delta U+W$, where $W$ is the work done by the system.
expansion	UK: /ɪkˈspænʃən/ US: /ɪkˈspænʃən/	A process in which the volume of a system increases.
compression	UK: /kəmˈpreʃən/ US: /kəmˈpreʃən/	A process in which the volume of a system decreases.
pressure-volume diagram	UK: /ˈpreʃə ˈvɒljuːm ˈdaɪəɡræm/ US: /ˈpreʃɚ ˈvɑːljum ˈdaɪəɡræm/	A graph showing pressure as a function of volume during a thermodynamic process.
isobaric process	UK: /ˌaɪsəʊˈbærɪk ˈprəʊses/ US: /ˌaɪsoʊˈbærɪk ˈprɑːses/	A thermodynamic process at constant pressure.
isochoric process	UK: /ˌaɪsəʊˈkɒrɪk ˈprəʊses/ US: /ˌaɪsoʊˈkɔːrɪk ˈprɑːses/	A thermodynamic process at constant volume.
isothermal process	UK: /ˌaɪsəʊˈθɜːməl ˈprəʊses/ US: /ˌaɪsoʊˈθɝːməl ˈprɑːses/	A thermodynamic process at constant temperature.
adiabatic process	UK: /ˌeɪdiəˈbætɪk ˈprəʊses/ US: /ˌeɪdiəˈbætɪk ˈprɑːses/	A thermodynamic process in which no energy is transferred by heating between the system and its surroundings.
cyclic process	UK: /ˈsaɪklɪk ˈprəʊses/ US: /ˈsaɪklɪk ˈprɑːses/	A process that returns a system to its initial thermodynamic state.
heat engine	UK: /hiːt ˈendʒɪn/ US: /hiːt ˈendʒən/	A cyclic device that absorbs energy by heating from a hot reservoir, does net work and rejects energy to a colder reservoir.
thermal reservoir	UK: /ˈθɜːməl ˈrezəvˌwɑː/ US: /ˈθɝːməl ˈrezəvˌwɑːr/	A body that can exchange energy without appreciable temperature change.
Carnot efficiency	UK: /kɑːˈnəʊ ɪˈfɪʃənsi/ US: /kɑːrˈnoʊ ɪˈfɪʃənsi/	The maximum theoretical efficiency of a reversible heat engine operating between two specified reservoir temperatures.
entropy	UK: /ˈentrəpi/ US: /ˈentrəpi/	A thermodynamic state function; in the statistical model used in the course, a macrostate of multiplicity Ω has entropy S = k_B ln Ω.
multiplicity	UK: /ˌmʌltɪˈplɪsɪti/ US: /ˌmʌltəˈplɪsɪti/	The number of microscopic arrangements corresponding to a macroscopic state.
second law of thermodynamics	UK: /ˈsekənd lɔː əv ˌθɜːməʊdaɪˈnæmɪks/ US: /ˈsekənd lɔː əv ˌθɝːmoʊdaɪˈnæmɪks/	In an isolated system, total entropy cannot decrease; this determines the allowed direction of spontaneous macroscopic processes.
reversible process	UK: /rɪˈvɜːsəbəl ˈprəʊses/ US: /rɪˈvɝːsəbəl ˈprɑːses/	An ideal process that can be reversed without net change to system and surroundings.
irreversible process	UK: /ɪrɪˈvɜːsəbəl ˈprəʊses/ US: /ˌɪrɪˈvɝːsəbəl ˈprɑːses/	A real process that cannot be exactly reversed without net changes.

B.5 Current and circuits

Term	Pronunciation	Definition
electric current	UK: /ɪˈlektrɪk ˈkərənt/ US: /ɪˈlektrɪk ˈkɝːənt/	The rate at which electric charge passes through a chosen cross-section.
conventional current	UK: /kənˈvenʃənəl ˈkərənt/ US: /kənˈvenʃənəl ˈkɝːənt/	The direction assigned to current as the direction in which positive charge would move.
charge carrier	UK: /tʃɑːdʒ ˈkærɪə/ US: /tʃɑːrdʒ ˈkæriər/	A mobile particle that transports electric charge.
potential difference	UK: /pəˈtenʃəl ˈdɪfrəns/ US: /pəˈtenʃəl ˈdɪfɚəns/	The difference in electric potential between two points, equal to the change in electric potential energy per unit charge.
electromotive force	UK: /ɪˌlektrəʊˈməʊtɪv fɔːs/ US: /ɪˌlektroʊˈmoʊtɪv fɔːrs/	The energy supplied by a source per unit charge passing through the source.
resistance	UK: /rɪˈzɪstəns/ US: /rɪˈzɪstəns/	For a component at a stated operating condition, the ratio of potential difference across it to current through it.
resistivity	UK: /ˌriːzɪˈstɪvəti/ US: /ˌriːzɪˈstɪvəti/	A material property defined for a uniform conductor by $\rho=RA/L$.
Ohm’s law	UK: /əʊmz lɔː/ US: /oʊmz lɔː/	For an ohmic conductor under constant physical conditions, current is proportional to potential difference.
ohmic conductor	UK: /ˈəʊmɪk kənˈdʌktə/ US: /ˈoʊmɪk kənˈdʌktɚ/	A conductor that obeys Ohm’s law over the range considered.
non-ohmic component	UK: /nɒn ˈəʊmɪk kəmˈpəʊnənt/ US: /nɑːn ˈoʊmɪk kəmˈpoʊnənt/	A component whose current is not proportional to potential difference.
current-voltage characteristic	UK: /ˈkərənt ˈvəʊltɪdʒ ˌkærɪktəˈrɪstɪk/ US: /ˈkɝːənt ˈvoʊltədʒ ˌkerəktɚˈɪstɪk/	A graph showing how current depends on potential difference for a component.
series circuit	UK: /ˈsɪəriːz ˈsɜːkɪt/ US: /ˈsɪriz ˈsɝːkət/	A circuit arrangement in which components carry the same current in one path.
parallel circuit	UK: /ˈpærəˌlel ˈsɜːkɪt/ US: /ˈperəˌlel ˈsɝːkət/	A circuit arrangement with branches across the same pair of nodes.
junction	UK: /ˈdʒəŋkʃən/ US: /ˈdʒʌŋkʃən/	A point in a circuit where current paths meet or divide.
cell	UK: /sel/ US: /sel/	A source that transfers energy from a non-electrical form to electrical energy and maintains an electromotive force.
battery	UK: /ˈbætəri/ US: /ˈbætɚi/	One or more cells connected to act as an electrical source.
internal resistance	UK: /ɪnˈtɜːnəl rɪˈzɪstəns/ US: /ˌɪnˈtɝːnəl rɪˈzɪstəns/	The effective resistance inside a source of electromotive force.
terminal potential difference	UK: /ˈtɜːmɪnəl pəˈtenʃəl ˈdɪfrəns/ US: /ˈtɝːmənəl pəˈtenʃəl ˈdɪfɚəns/	The potential difference measured across the terminals of a source.
lost volts	UK: /lɒst vɒlts/ US: /lɔːst voʊlts/	The potential difference across a source’s internal resistance when current flows.
electrical power	UK: /ɪˈlektrɪkəl ˈpaʊə/ US: /ɪˈlektrɪkəl ˈpaʊɚ/	The rate at which electrical energy is transferred.
short circuit	UK: /ʃɔːt ˈsɜːkɪt/ US: /ʃɔːrt ˈsɝːkət/	A very low-resistance path that can produce a large current.
potential divider	UK: /pəˈtenʃəl dɪˈvaɪdə/ US: /pəˈtenʃəl dɪˈvaɪdɚ/	A series circuit used to provide a chosen fraction of an input potential difference.

C.1 Simple harmonic motion

Term	Pronunciation	Definition
oscillation	UK: /ˌɒsɪˈleɪʃən/ US: /ˌɑːsəˈleɪʃən/	Repeated motion about an equilibrium position.
periodic motion	UK: /ˌpɪərɪˈɒdɪk ˈməʊʃən/ US: /ˌpɪriˈɑːdɪk ˈmoʊʃən/	Motion that repeats after equal time intervals.
equilibrium position	UK: /ˌiːkwɪˈlɪbrɪəm pəˈzɪʃən/ US: /ˌiːkwəˈlɪbriəm pəˈzɪʃən/	The position at which the resultant force is zero.
displacement	UK: /dɪˈspleɪsmənt/ US: /dɪˈspleɪsmənt/	The signed distance from the equilibrium position.
amplitude	UK: /ˈæmplɪˌtjuːd/ US: /ˈæmpləˌtuːd/	The maximum magnitude of an oscillating quantity relative to its equilibrium value.
time period	UK: /taɪm ˈpɪərɪəd/ US: /taɪm ˈpɪriəd/	The time taken for one complete oscillation.
frequency	UK: /ˈfriːkwənsi/ US: /ˈfriːkwənsi/	The number of complete oscillations per unit time.
angular frequency	UK: /ˈænɡjʊlə ˈfriːkwənsi/ US: /ˈæŋɡjəlɚ ˈfriːkwənsi/	The phase change per unit time in radians.
simple harmonic motion	UK: /ˈsɪmpəl hɑːˈmɒnɪk ˈməʊʃən/ US: /ˈsɪmpəl hɑːrˈmɑːnɪk ˈmoʊʃən/	Oscillation in which acceleration is proportional to displacement from equilibrium and directed oppositely to it.
restoring force	UK: /rɪˈstɔːrɪŋ fɔːs/ US: /rɪˈstɔːrɪŋ fɔːrs/	A force directed towards the equilibrium position.
phase	UK: /feɪz/ US: /feɪz/	A quantity that specifies the position within an oscillation cycle relative to a chosen reference.
phase angle	UK: /feɪz ˈæŋɡəl/ US: /feɪz ˈæŋɡəl/	The angular measure used to specify phase.
in phase	UK: /ɪn feɪz/ US: /ɪn feɪz/	Having the same phase at the same time.
antiphase	UK: /ˈæntɪfeɪz/ US: /ˈæntɪfeɪz/	Differing in phase by half a cycle or pi radians.
mass-spring system	UK: /mæs sprɪŋ ˈsɪstəm/ US: /mæs sprɪŋ ˈsɪstəm/	An oscillator consisting of a mass attached to an elastic spring.
simple pendulum	UK: /ˈsɪmpəl ˈpendjʊləm/ US: /ˈsɪmpəl ˈpendʒələm/	An ideal pendulum with a point mass on a light inextensible string.
total energy	UK: /ˈtəʊtəl ˈenədʒi/ US: /ˈtoʊtəl ˈenɚdʒi/	The constant sum of kinetic and potential energies in undamped SHM.

C.2 Wave model

Term	Pronunciation	Definition
wave	UK: /weɪv/ US: /weɪv/	A disturbance that propagates and transfers energy and information without a resultant transfer of matter.
travelling wave	UK: /ˈtrævlɪŋ weɪv/ US: /ˈtrævəlɪŋ weɪv/	A wave pattern that propagates through space or a medium.
transverse wave	UK: /trænsˈvɜːs weɪv/ US: /trænzˈvɝːs weɪv/	A wave in which the relevant oscillation is perpendicular to the direction of propagation.
longitudinal wave	UK: /ˌlɒndʒɪˈtjuːdɪnəl weɪv/ US: /ˌlɑːndʒəˈtuːdənəl weɪv/	A wave in which the relevant oscillation is parallel to the direction of propagation.
mechanical wave	UK: /mɪˈkænɪkəl weɪv/ US: /məˈkænɪkəl weɪv/	A wave that requires a material medium.
electromagnetic wave	UK: /ɪˌlektrəʊməɡˈnetɪk weɪv/ US: /ˌɪˌlektroʊmæɡˈnetɪk weɪv/	A transverse wave of oscillating electric and magnetic fields.
wavelength	UK: /ˈweɪvˌleŋθ/ US: /ˈweɪvˌleŋθ/	The shortest distance, measured along the direction of propagation, between two points in the same phase.
frequency	UK: /ˈfriːkwənsi/ US: /ˈfriːkwənsi/	The number of complete wave cycles passing a point per unit time.
period	UK: /ˈpɪərɪəd/ US: /ˈpɪriəd/	The time taken for one complete cycle.
wave speed	UK: /weɪv spiːd/ US: /weɪv spiːd/	The speed at which a specified phase of a wave propagates.
amplitude	UK: /ˈæmplɪˌtjuːd/ US: /ˈæmpləˌtuːd/	The maximum magnitude of an oscillating quantity relative to its equilibrium value.
phase difference	UK: /feɪz ˈdɪfrəns/ US: /feɪz ˈdɪfɚəns/	The difference in phase between two oscillations or points on a wave.
compression	UK: /kəmˈpreʃən/ US: /kəmˈpreʃən/	A region of increased pressure and density in a longitudinal wave.
rarefaction	UK: /reəˈfækʃən/ US: /ˌrerəˈfækʃən/	A region of decreased pressure and density in a longitudinal wave.
sound wave	UK: /saʊnd weɪv/ US: /saʊnd weɪv/	A mechanical wave consisting of pressure and density variations in a material medium.
electromagnetic spectrum	UK: /ɪˌlektrəʊməɡˈnetɪk ˈspektrəm/ US: /ˌɪˌlektroʊmæɡˈnetɪk ˈspektrəm/	The complete range of electromagnetic wavelengths and frequencies.
energy transfer	UK: /ˈenədʒi ˈtrænsfɜː/ US: /ˈenɚdʒi ˈtrænsfɝː/	The movement of energy from one system or part of a system to another, for example by work, heating or radiation.

C.3 Wave phenomena

Term	Pronunciation	Definition
wavefront	UK: /ˈweɪvfrʌnt/ US: /ˈweɪvfrʌnt/	A line or surface joining points of equal phase.
ray	UK: /reɪ/ US: /reɪ/	A geometrical line normal to wavefronts that indicates the local direction of wave propagation and energy transfer.
boundary	UK: /ˈbaʊndri/ US: /ˈbaʊndɚi/	The interface between two media or regions.
reflection	UK: /rɪˈflekʃən/ US: /rɪˈflekʃən/	The return of a wave into its original medium at a boundary.
refraction	UK: /rɪˈfrækʃən/ US: /rɪˈfrækʃən/	A change in wave speed on entering another medium, generally accompanied by a change in direction except at normal incidence.
transmission	UK: /ˌtrænˈsmɪʃən/ US: /trænˈsmɪʃən/	The passage of part of a wave and its energy through a boundary into another region or medium.
refractive index	UK: /rɪˈfræktɪv ˈɪndeks/ US: /rəˈfræktɪv ˈɪndeks/	For light in a medium, the ratio of its speed in vacuum to its phase speed in the medium.
Snell’s law	UK: /snelz lɔː/ US: /snelz lɔː/	The relation between angles of incidence and refraction and refractive indices.
angle of incidence	UK: /ˈæŋɡəl əv ˈɪnsɪdəns/ US: /ˈæŋɡəl əv ˈɪnsədəns/	The angle between an incident ray and the normal.
angle of refraction	UK: /ˈæŋɡəl əv rɪˈfrækʃən/ US: /ˈæŋɡəl əv rɪˈfrækʃən/	The angle between a refracted ray and the normal.
critical angle	UK: /ˈkrɪtɪkəl ˈæŋɡəl/ US: /ˈkrɪtɪkəl ˈæŋɡəl/	For a wave travelling from higher to lower refractive index, the angle of incidence that gives a refracted angle of $90^\circ$.
total internal reflection	UK: /ˈtəʊtəl ɪnˈtɜːnəl rɪˈflekʃən/ US: /ˈtoʊtəl ˌɪnˈtɝːnəl rɪˈflekʃən/	Complete reflection at a boundary when a wave travels from higher to lower refractive index and the incident angle exceeds the critical angle.
diffraction	UK: /dɪˈfrækʃən/ US: /dɪˈfrækʃən/	The spreading and bending of waves around obstacles or through apertures, most evident when dimensions are comparable with the wavelength.
aperture	UK: /ˈæpətʃə/ US: /ˈæpɚtʃɚ/	An opening through which a wave passes.
superposition	UK: /ˌsuːpəpəˈzɪʃən/ US: /ˌsuːpərpəˈzɪʃən/	The principle that the resultant displacement or field at a point is the algebraic or vector sum of the individual contributions.
interference	UK: /ˌɪntəˈfɪərəns/ US: /ˌɪntɚˈfɪrəns/	The spatial redistribution of wave amplitude or intensity produced by superposition of coherent waves.
constructive interference	UK: /kənˈstrəktɪv ˌɪntəˈfɪərəns/ US: /kənˈstrʌktɪv ˌɪntɚˈfɪrəns/	Interference that produces increased resultant amplitude.
destructive interference	UK: /dɪˈstrəktɪv ˌɪntəˈfɪərəns/ US: /dɪˈstrʌktɪv ˌɪntɚˈfɪrəns/	Interference that produces reduced or zero resultant amplitude.
coherent sources	UK: /kəʊˈhɪərənt ˈsɔːsɪz/ US: /koʊˈhɪrənt ˈsɔːrsəz/	Sources that produce waves of the same frequency with a constant phase difference.
path difference	UK: /pɑːθ ˈdɪfrəns/ US: /pæθ ˈdɪfɚəns/	The difference in distances travelled by two waves to a point.
double-slit interference	UK: /ˈdəbəl slɪt ˌɪntəˈfɪərəns/ US: /ˈdʌbəl slɪt ˌɪntɚˈfɪrəns/	An interference pattern produced by two narrow coherent openings.
fringe spacing	UK: /frɪndʒ ˈspeɪsɪŋ/ US: /frɪndʒ ˈspeɪsɪŋ/	The distance between adjacent bright or dark interference fringes.
diffraction grating	UK: /dɪˈfrækʃən ˈɡreɪtɪŋ/ US: /dɪˈfrækʃən ˈɡreɪtɪŋ/	An optical element containing many equally spaced parallel slits.
order	UK: /ˈɔːdə/ US: /ˈɔːrdɚ/	An integer label identifying an interference maximum.

C.4 Standing waves and resonance

Term	Pronunciation	Definition
standing wave	UK: /ˈstændɪŋ weɪv/ US: /ˈstændɪŋ weɪv/	A stationary oscillation pattern formed by superposition of waves of the same frequency travelling in opposite directions.
node	UK: /nəʊd/ US: /noʊd/	A point in a standing wave at which the relevant oscillating quantity has zero amplitude.
antinode	UK: /ˈæntɪnəʊd/ US: /ˈæntɪnoʊd/	A point in a standing wave at which the relevant oscillating quantity has maximum amplitude.
fundamental frequency	UK: /ˌfəndəˈmentəl ˈfriːkwənsi/ US: /ˌfʌndəˈmentəl ˈfriːkwənsi/	The lowest natural frequency of a standing-wave system.
harmonic	UK: /hɑːˈmɒnɪk/ US: /hɑːrˈmɑːnɪk/	A permitted oscillation mode whose frequency is an integer multiple of the fundamental frequency.
overtone	UK: /ˈəʊvəˌtəʊn/ US: /ˈoʊvɚˌtoʊn/	Any natural frequency of a system above its fundamental frequency.
mode	UK: /məʊd/ US: /moʊd/	A permitted pattern of oscillation determined by boundary conditions.
boundary condition	UK: /ˈbaʊndri kənˈdɪʃən/ US: /ˈbaʊndɚi kənˈdɪʃən/	A physical constraint imposed at the boundary of a wave system.
fixed end	UK: /fɪkst end/ US: /fɪkst end/	A boundary at which displacement must be zero.
free end	UK: /friː end/ US: /friː end/	A boundary at which displacement can be maximum.
open pipe	UK: /ˈəʊpən paɪp/ US: /ˈoʊpən paɪp/	An air column with an open end that acts as a displacement antinode.
closed pipe	UK: /kləʊzd paɪp/ US: /kloʊzd paɪp/	An air column with a closed end that acts as a displacement node.
natural frequency	UK: /ˈnætʃrəl ˈfriːkwənsi/ US: /ˈnætʃɚəl ˈfriːkwənsi/	A frequency at which a system oscillates freely.
driving frequency	UK: /ˈdraɪvɪŋ ˈfriːkwənsi/ US: /ˈdraɪvɪŋ ˈfriːkwənsi/	The frequency of an external periodic force.
resonance	UK: /ˈrezənəns/ US: /ˈrezənəns/	A large steady-state response when a system is driven at or near one of its natural frequencies.
damping	UK: /ˈdæmpɪŋ/ US: /ˈdæmpɪŋ/	A process that removes mechanical energy from an oscillator and reduces its amplitude.
light damping	UK: /laɪt ˈdæmpɪŋ/ US: /laɪt ˈdæmpɪŋ/	Weak damping that allows oscillations of gradually decreasing amplitude.
critical damping	UK: /ˈkrɪtɪkəl ˈdæmpɪŋ/ US: /ˈkrɪtɪkəl ˈdæmpɪŋ/	The minimum damping that returns a displaced system to equilibrium without oscillation.
overdamping	UK: /ˌəʊvəˈdæmpɪŋ/ US: /ˌoʊvərˈdæmpɪŋ/	Damping stronger than critical, producing a slow non-oscillatory return.

C.5 Doppler effect

Term	Pronunciation	Definition
Doppler effect	UK: /ˈdɒplə ɪˈfekt/ US: /ˈdɑːplər ɪˈfekt/	The change in observed frequency caused by relative radial motion between source and observer.
source frequency	UK: /sɔːs ˈfriːkwənsi/ US: /sɔːrs ˈfriːkwənsi/	The frequency emitted by the source in its rest frame.
observed frequency	UK: /əbˈzɜːvd ˈfriːkwənsi/ US: /əbˈzɝːvd ˈfriːkwənsi/	The frequency measured by an observer.
moving source	UK: /ˈmuːvɪŋ sɔːs/ US: /ˈmuːvɪŋ sɔːrs/	A source whose position changes relative to the medium or observer.
moving observer	UK: /ˈmuːvɪŋ əbˈzɜːvə/ US: /ˈmuːvɪŋ əbˈzɝːvɚ/	An observer moving relative to the medium or source.
radial velocity	UK: /ˈreɪdɪəl vəˈlɒsɪti/ US: /ˈreɪdiəl vəˈlɑːsəti/	The component of velocity along the line of sight.
redshift	UK: /ˈredʃɪft/ US: /ˈredʃɪft/	A shift of spectral features towards longer wavelengths and lower frequencies.
blueshift	UK: /ˈbluːʃɪft/ US: /ˈbluːʃɪft/	A shift of spectral features towards shorter wavelengths and higher frequencies.
fractional frequency shift	UK: /ˈfrækʃənəl ˈfriːkwənsi ʃɪft/ US: /ˈfrækʃənəl ˈfriːkwənsi ʃɪft/	The frequency change divided by the original frequency.
fractional wavelength shift	UK: /ˈfrækʃənəl ˈweɪvˌleŋθ ʃɪft/ US: /ˈfrækʃənəl ˈweɪvˌleŋθ ʃɪft/	The wavelength change divided by the original wavelength.
line of sight	UK: /laɪn əv saɪt/ US: /laɪn əv saɪt/	The straight direction from observer to source.
spectral line	UK: /ˈspektrəl laɪn/ US: /ˈspektrəl laɪn/	A narrow wavelength feature produced by emission or absorption.

D.1 Gravitational fields

Term	Pronunciation	Definition
gravitational field	UK: /ˌɡrævɪˈteɪʃənəl fiːld/ US: /ˌɡrævɪˈteɪʃənəl fiːld/	A region in which a mass experiences gravitational force.
gravitational field strength	UK: /ˌɡrævɪˈteɪʃənəl fiːld streŋθ/ US: /ˌɡrævɪˈteɪʃənəl fiːld streŋθ/	The gravitational force per unit mass on a small test mass; it is a vector.
universal law of gravitation	UK: /ˌjuːnɪˈvɜːsəl lɔː əv ˌɡrævɪˈteɪʃən/ US: /ˌjuːnəˈvɝːsəl lɔː əv ˌɡrævɪˈteɪʃən/	Newton’s inverse-square law for the gravitational force between two point masses.
gravitational constant	UK: /ˌɡrævɪˈteɪʃənəl ˈkɒnstənt/ US: /ˌɡrævɪˈteɪʃənəl ˈkɑːnstənt/	The universal proportionality constant in Newton’s law of gravitation.
point mass	UK: /pɔɪnt mæs/ US: /pɔɪnt mæs/	An idealized body whose dimensions are negligible compared with the distances relevant to the problem.
spherical mass	UK: /ˈsferɪkəl mæs/ US: /ˈsferɪkəl mæs/	A spherically symmetric mass distribution treated externally as a point mass.
radial field	UK: /ˈreɪdɪəl fiːld/ US: /ˈreɪdiəl fiːld/	A field whose vectors point directly towards or away from one centre.
uniform gravitational field	UK: /ˈjuːnɪˌfɔːm ˌɡrævɪˈteɪʃənəl fiːld/ US: /ˈjuːnəˌfɔːrm ˌɡrævɪˈteɪʃənəl fiːld/	A gravitational field with constant magnitude and direction.
field line	UK: /fiːld laɪn/ US: /fiːld laɪn/	An imaginary curve whose tangent at each point gives the local direction of the field.
superposition	UK: /ˌsuːpəpəˈzɪʃən/ US: /ˌsuːpərpəˈzɪʃən/	The principle that the resultant displacement or field at a point is the algebraic or vector sum of the individual contributions.
gravitational potential energy	UK: /ˌɡrævɪˈteɪʃənəl pəˈtenʃəl ˈenədʒi/ US: /ˌɡrævɪˈteɪʃənəl pəˈtenʃəl ˈenɚdʒi/	Energy associated with the configuration of masses.
gravitational potential	UK: /ˌɡrævɪˈteɪʃənəl pəˈtenʃəl/ US: /ˌɡrævɪˈteɪʃənəl pəˈtenʃəl/	The gravitational potential energy per unit mass, with the chosen reference value.
potential gradient	UK: /pəˈtenʃəl ˈɡreɪdɪənt/ US: /pəˈtenʃəl ˈɡreɪdiənt/	The rate of change of potential with position; its negative gives field strength.
equipotential surface	UK: /ˌiːkwɪpəˈtenʃəl ˈsɜːfɪs/ US: /ˌiːkwɪpəˈtenʃəl ˈsɝːfəs/	A surface on which gravitational potential is constant.
orbital motion	UK: /ˈɔːbɪtəl ˈməʊʃən/ US: /ˈɔːrbətəl ˈmoʊʃən/	Motion of one body around another under gravity.
circular orbit	UK: /ˈsɜːkjʊlə ˈɔːbɪt/ US: /ˈsɝːkjələr ˈɔːrbət/	An orbit of constant radius.
orbital speed	UK: /ˈɔːbɪtəl spiːd/ US: /ˈɔːrbətəl spiːd/	The tangential speed of a body in orbit.
orbital period	UK: /ˈɔːbɪtəl ˈpɪərɪəd/ US: /ˈɔːrbətəl ˈpɪriəd/	The time taken to complete one orbit.
satellite	UK: /ˈsætəˌlaɪt/ US: /ˈsætəˌlaɪt/	A body that orbits another body.
geostationary orbit	UK: /ˌdʒiːəʊˈsteɪʃənəri ˈɔːbɪt/ US: /ˌdʒiːoʊˈsteɪʃəneri ˈɔːrbət/	A circular equatorial orbit whose period equals Earth’s rotation period and direction is prograde.
escape speed	UK: /ɪˈskeɪp spiːd/ US: /ɪˈskeɪp spiːd/	The minimum initial speed required to reach infinity with zero final speed when only the stated inverse-square gravitational field acts.
Kepler’s laws	UK: /ˈkepləz lɔːz/ US: /ˈkeplərz lɔːz/	Three empirical laws describing planetary orbits.
apparent weightlessness	UK: /əˈpærənt ˈweɪtləsnəs/ US: /əˈperənt ˈweɪtləsnəs/	The condition in which the contact force supporting a body is zero, even though gravity may still act.
binding energy	UK: /ˈbaɪndɪŋ ˈenədʒi/ US: /ˈbaɪndɪŋ ˈenɚdʒi/	The positive energy required to separate a bound system into specified free constituents.

D.2 Electric and magnetic fields

Term	Pronunciation	Definition
electric charge	UK: /ɪˈlektrɪk tʃɑːdʒ/ US: /ɪˈlektrɪk tʃɑːrdʒ/	A property of matter that determines electric interactions.
positive charge	UK: /ˈpɒzɪtɪv tʃɑːdʒ/ US: /ˈpɑːzətɪv tʃɑːrdʒ/	One of the two types of electric charge, conventionally carried by protons.
negative charge	UK: /ˈneɡətɪv tʃɑːdʒ/ US: /ˈneɡətɪv tʃɑːrdʒ/	One of the two types of electric charge, carried by electrons.
neutral body	UK: /ˈnjuːtrəl ˈbɒdi/ US: /ˈnuːtrəl ˈbɑːdi/	A body with zero net electric charge.
conservation of charge	UK: /ˌkɒnsəˈveɪʃən əv tʃɑːdʒ/ US: /ˌkɑːnsɚˈveɪʃən əv tʃɑːrdʒ/	The total electric charge of an isolated system remains constant.
quantization of charge	UK: /ˌkwɒntaɪˈzeɪʃən əv tʃɑːdʒ/ US: /ˌkwɑːntaɪˈzeɪʃən əv tʃɑːrdʒ/	The fact that net charge occurs in discrete multiples of the elementary charge.
elementary charge	UK: /ˌelɪˈmentəri tʃɑːdʒ/ US: /ˌeləˈmentri tʃɑːrdʒ/	The positive constant e equal to the magnitude of the charge of a proton or electron.
Millikan’s oil-drop experiment	UK: /ˈmɪlɪkənz ˈɔɪl drɒp ɪkˌsperɪmənt/ US: /ˈmɪlɪkənz ˈɔɪl drɑːp ɪkˌsperɪmənt/	The experiment that provided evidence for quantized electric charge.
charging by friction	UK: /ˈtʃɑːdʒɪŋ baɪ ˈfrɪkʃən/ US: /ˈtʃɑːrdʒɪŋ baɪ ˈfrɪkʃən/	Transfer of electrons when different materials are rubbed together.
charging by contact	UK: /ˈtʃɑːdʒɪŋ baɪ kənˈtækt/ US: /ˈtʃɑːrdʒɪŋ baɪ ˈkɑːnˌtækt/	Transfer and redistribution of charge when conductors touch.
electrostatic induction	UK: /ɪˌlektrəʊˈstætɪk ɪnˈdəkʃən/ US: /ˌɪˌlektroʊˈstætɪk ˌɪnˈdʌkʃən/	The redistribution of charge in a conductor caused by an external electric field, without direct contact with the inducing body.
grounding	UK: /ˈɡraʊndɪŋ/ US: /ˈɡraʊndɪŋ/	Connecting a conductor to Earth so charge can flow to or from it.
Coulomb’s law	UK: /ˈkuːlɒmz lɔː/ US: /ˈkuːlɑːmz lɔː/	The inverse-square relation for the magnitude and line of action of the electrostatic force between point charges.
permittivity	UK: /ˌpɜːmɪˈtɪvɪti/ US: /ˌpɝːmɪˈtɪvəti/	A property of a medium that determines its electric response and the strength of electric fields produced by charges within it.
electric field	UK: /ɪˈlektrɪk fiːld/ US: /ɪˈlektrɪk fiːld/	A vector field defined by the electric force per unit positive test charge.
electric field strength	UK: /ɪˈlektrɪk fiːld streŋθ/ US: /ɪˈlektrɪk fiːld streŋθ/	The electric force per unit positive test charge at a point.
test charge	UK: /test tʃɑːdʒ/ US: /test tʃɑːrdʒ/	An idealized small positive charge used to define or probe an electric field without significantly disturbing its sources.
electric field line	UK: /ɪˈlektrɪk fiːld laɪn/ US: /ɪˈlektrɪk fiːld laɪn/	An imaginary curve whose tangent gives the electric-field direction, conventionally the force direction on a positive test charge.
field-line density	UK: /fiːld laɪn ˈdensɪti/ US: /fiːld laɪn ˈdensəti/	A qualitative graphical indication of relative field magnitude; it is not itself a physical quantity.
uniform electric field	UK: /ˈjuːnɪˌfɔːm ɪˈlektrɪk fiːld/ US: /ˈjuːnəˌfɔːrm ɪˈlektrɪk fiːld/	An electric field whose vector has the same magnitude and direction throughout the region considered.
parallel plates	UK: /ˈpærəˌlel pleɪts/ US: /ˈperəˌlel pleɪts/	Two conducting plates used to produce an approximately uniform electric field.
edge effect	UK: /edʒ ɪˈfekt/ US: /edʒ ɪˈfekt/	The curvature and non-uniformity of field lines near the edges of finite plates.
electric potential energy	UK: /ɪˈlektrɪk pəˈtenʃəl ˈenədʒi/ US: /ɪˈlektrɪk pəˈtenʃəl ˈenɚdʒi/	Energy associated with the configuration of electric charges.
electric potential	UK: /ɪˈlektrɪk pəˈtenʃəl/ US: /ɪˈlektrɪk pəˈtenʃəl/	The electric potential energy per unit charge at a point, relative to a chosen zero.
potential difference	UK: /pəˈtenʃəl ˈdɪfrəns/ US: /pəˈtenʃəl ˈdɪfɚəns/	The difference in electric potential between two points, equal to the change in electric potential energy per unit charge.
equipotential surface	UK: /ˌiːkwɪpəˈtenʃəl ˈsɜːfɪs/ US: /ˌiːkwɪpəˈtenʃəl ˈsɝːfəs/	A surface on which electric potential is constant.
conductor	UK: /kənˈdʌktə/ US: /kənˈdʌktɚ/	A material containing mobile charge carriers.
electrostatic equilibrium	UK: /ɪˌlektrəʊˈstætɪk ˌiːkwɪˈlɪbrɪəm/ US: /ˌɪˌlektroʊˈstætɪk ˌiːkwəˈlɪbriəm/	A state in which charge in a conductor has no macroscopic motion and the electric field inside the conducting material is zero.
magnetic field	UK: /mæɡˈnetɪk fiːld/ US: /mæɡˈnetɪk fiːld/	A vector field that exerts forces on moving charges, electric currents and magnetic dipoles.
magnetic field line	UK: /mæɡˈnetɪk fiːld laɪn/ US: /mæɡˈnetɪk fiːld laɪn/	A closed curve whose tangent gives the local direction of the magnetic field.
bar magnet	UK: /bɑː ˈmæɡnɪt/ US: /bɑːr ˈmæɡnət/	A permanent magnet with distinguishable north and south poles.
current-carrying wire	UK: /ˈkərənt ˈkæriɪŋ ˈwaɪə/ US: /ˈkɝːənt ˈkæriɪŋ ˈwaɪɚ/	A wire through which electric current flows.
circular coil	UK: /ˈsɜːkjʊlə kɔɪl/ US: /ˈsɝːkjələr kɔɪl/	A current-carrying conductor formed into a circular loop.
solenoid	UK: /ˈsəʊlənɔɪd/ US: /ˈsoʊlənɔɪd/	A long helical coil that produces an approximately uniform internal magnetic field.
right-hand grip rule	UK: /raɪt hænd ɡrɪp ruːl/ US: /raɪt hænd ɡrɪp ruːl/	A rule in which the right thumb points along conventional current and the curled fingers show the magnetic-field direction around it.

D.3 Motion in electromagnetic fields

Term	Pronunciation	Definition
charged particle	UK: /tʃɑːdʒd ˈpɑːtɪkəl/ US: /tʃɑːrdʒd ˈpɑːrtəkəl/	A particle with non-zero net electric charge.
electric force	UK: /ɪˈlektrɪk fɔːs/ US: /ɪˈlektrɪk fɔːrs/	The force exerted on a charge by an electric field.
magnetic force	UK: /mæɡˈnetɪk fɔːs/ US: /mæɡˈnetɪk fɔːrs/	The force exerted by a magnetic field on a moving charge, current or magnetic dipole.
magnetic flux density	UK: /mæɡˈnetɪk fləks ˈdensɪti/ US: /mæɡˈnetɪk flʌks ˈdensəti/	The vector magnetic-field quantity B; its magnitude determines magnetic-force magnitudes in relations such as F = qvB sin θ and F = BIL sin θ, where q denotes charge magnitude.
uniform electric field	UK: /ˈjuːnɪˌfɔːm ɪˈlektrɪk fiːld/ US: /ˈjuːnəˌfɔːrm ɪˈlektrɪk fiːld/	An electric field whose vector has the same magnitude and direction throughout the region considered.
uniform magnetic field	UK: /ˈjuːnɪˌfɔːm mæɡˈnetɪk fiːld/ US: /ˈjuːnəˌfɔːrm mæɡˈnetɪk fiːld/	A magnetic field whose vector has the same magnitude and direction throughout the region considered.
parabolic path	UK: /ˌpærəˈbɒlɪk pɑːθ/ US: /ˌperəˈbɑːlɪk pæθ/	The trajectory of a particle with uniform motion in one direction and constant acceleration in a perpendicular direction.
circular path	UK: /ˈsɜːkjʊlə pɑːθ/ US: /ˈsɝːkjələr pæθ/	The path of a charge moving perpendicular to a uniform magnetic field.
helical path	UK: /ˈhelɪkəl pɑːθ/ US: /ˈhelɪkəl pæθ/	A helical trajectory produced when a charged particle has velocity components both parallel and perpendicular to a uniform magnetic field.
charge-to-mass ratio	UK: /tʃɑːdʒ tə mæs ˈreɪʃiəʊ/ US: /tʃɑːrdʒ tuː mæs ˈreɪʃioʊ/	The algebraic electric charge of a particle divided by its mass; its magnitude is often inferred from deflection data.
orbital radius	UK: /ˈɔːbɪtəl ˈreɪdɪəs/ US: /ˈɔːrbətəl ˈreɪdiəs/	The radius of a charged particle’s circular path in a magnetic field.
velocity selector	UK: /vəˈlɒsɪti sɪˈlektə/ US: /vəˈlɑːsəti sɪˈlektər/	A crossed-field device in which electric and magnetic forces cancel for particles of one selected speed.
crossed fields	UK: /krɒst fiːldz/ US: /krɔːst fiːldz/	Electric and magnetic fields arranged perpendicular to each other.
current-carrying conductor	UK: /ˈkərənt ˈkæriɪŋ kənˈdʌktə/ US: /ˈkɝːənt ˈkæriɪŋ kənˈdʌktɚ/	A conductor carrying electric current and therefore subject to magnetic force in a field.
parallel currents	UK: /ˈpærəˌlel ˈkʌrənts/ US: /ˈperəˌlel ˈkɝːənts/	Currents flowing in parallel conductors.
attractive force	UK: /əˈtræktɪv fɔːs/ US: /əˈtræktɪv fɔːrs/	A force drawing two bodies or wires towards each other.
repulsive force	UK: /rɪˈpʌlsɪv fɔːs/ US: /riˈpʌlsɪv fɔːrs/	A force pushing two bodies or wires apart.
right-hand rule	UK: /raɪt hænd ruːl/ US: /raɪt hænd ruːl/	A hand rule used to determine magnetic-field or force direction.

D.4 Induction

Term	Pronunciation	Definition
electromagnetic induction	UK: /ɪˌlektrəʊməɡˈnetɪk ɪnˈdəkʃən/ US: /ˌɪˌlektroʊmæɡˈnetɪk ˌɪnˈdʌkʃən/	The production of an emf by a changing magnetic flux linkage.
induced emf	UK: /ɪnˈdjuːst ˌiː em ˈef/ US: /ɪnˈduːst ˌiː em ˈef/	An electromotive force produced by electromagnetic induction.
induced current	UK: /ɪnˈdjuːst ˈkərənt/ US: /ɪnˈduːst ˈkɝːənt/	A current caused by an induced emf in a closed circuit.
magnetic flux	UK: /mæɡˈnetɪk fləks/ US: /mæɡˈnetɪk flʌks/	For a uniform magnetic field through a plane area, $\Phi=BA\cos\theta$, where $\theta$ is the angle between $\boldsymbol{B}$ and the area normal.
flux linkage	UK: /fləks ˈlɪŋkɪdʒ/ US: /flʌks ˈlɪŋkədʒ/	The product of the number of turns and magnetic flux through one turn.
area normal	UK: /ˈeəriə ˈnɔːməl/ US: /ˈeriə ˈnɔːrməl/	A vector perpendicular to a surface used to define flux orientation.
Faraday’s law	UK: /ˈfærədeɪz lɔː/ US: /ˈfærədeɪz lɔː/	The induced emf around a circuit equals the negative rate of change of magnetic flux linkage.
Lenz’s law	UK: /ˈlentsɪz lɔː/ US: /ˈlentsɪz lɔː/	The direction of an induced current is such that its magnetic effect opposes the change in flux that produces it.
motional emf	UK: /ˈməʊʃənəl ˌiː em ˈef/ US: /ˈmoʊʃənəl ˌiː em ˈef/	An emf produced when a conductor moves through a magnetic field.
relative motion	UK: /ˈrelətɪv ˈməʊʃən/ US: /ˈrelətɪv ˈmoʊʃən/	Motion of a conductor and magnetic field relative to each other.
generator	UK: /ˈdʒenəˌreɪtə/ US: /ˈdʒenɚˌeɪtɚ/	A device that converts mechanical energy into electrical energy by induction.
alternating emf	UK: /ˈɔːltəneɪtɪŋ ˌiː em ˈef/ US: /ˈɔːltɚˌneɪtɪŋ ˌiː em ˈef/	An induced emf that reverses polarity periodically.
alternating current	UK: /ˈɔːltəneɪtɪŋ ˈkərənt/ US: /ˈɔːltɚˌneɪtɪŋ ˈkɝːənt/	An electric current that reverses direction periodically.
coil	UK: /kɔɪl/ US: /kɔɪl/	A conductor wound into one or more loops.
rectangular coil	UK: /rekˈtænɡjʊlə kɔɪl/ US: /rekˈtæŋɡjəlɚ kɔɪl/	A coil whose turns have rectangular shape.
rotating coil	UK: /rəʊˈteɪtɪŋ kɔɪl/ US: /ˈroʊˌteɪtɪŋ kɔɪl/	A coil rotating in a magnetic field to produce changing flux.
self-induction	UK: /self ɪnˈdəkʃən/ US: /self ˌɪnˈdʌkʃən/	Induction in a circuit caused by a change in its own current.
back emf	UK: /bæk ˌiː em ˈef/ US: /bæk ˌiː em ˈef/	An induced emf that opposes the applied change producing it.
energy conservation	UK: /ˈenədʒi ˌkɒnsəˈveɪʃən/ US: /ˈenɚdʒi ˌkɑːnsɚˈveɪʃən/	The principle explaining why induced effects oppose the change that creates them.
weber	UK: /ˈveɪbə/ US: /ˈveɪbər/	The SI unit of magnetic flux.

E.1 Structure of the atom

Term	Pronunciation	Definition
atom	UK: /ˈætəm/ US: /ˈætəm/	The smallest electrically neutral or ionizable unit of an element that retains its chemical identity.
nucleus	UK: /ˈnjuːklɪəs/ US: /ˈnuːkliəs/	The small, dense central part of an atom, containing protons and neutrons and carrying positive charge.
electron	UK: /ɪˈlektrɒn/ US: /ˌɪˈlektrɑːn/	A negatively charged elementary particle found in atoms.
proton	UK: /ˈprəʊtɒn/ US: /ˈproʊtɑːn/	A positively charged nucleon in an atomic nucleus.
neutron	UK: /ˈnjuːtrɒn/ US: /ˈnuːtrɑːn/	An electrically neutral nucleon in an atomic nucleus.
nucleon	UK: /ˈnjuːkliɒn/ US: /ˈnuːkliɑːn/	A proton or neutron.
nucleon number	UK: /ˈnjuːkliɒn ˈnəmbə/ US: /ˈnuːkliɑːn ˈnʌmbɚ/	The total number of protons and neutrons in a nucleus.
proton number	UK: /ˈprəʊtɒn ˈnəmbə/ US: /ˈproʊtɑːn ˈnʌmbɚ/	The number of protons in a nucleus.
nuclear notation	UK: /ˈnjuːklɪə nəʊˈteɪʃən/ US: /ˈnuːkliɚ noʊˈteɪʃən/	The symbolic notation showing proton number, nucleon number and element.
Rutherford scattering	UK: /ˈrʌðəfəd ˈskætərɪŋ/ US: /ˈrʌðərfərd ˈskætɚɪŋ/	Scattering of alpha particles by nuclei, revealing concentrated positive charge.
alpha particle	UK: /ˈælfə ˈpɑːtɪkəl/ US: /ˈælfə ˈpɑːrtəkəl/	A helium nucleus containing two protons and two neutrons.
distance of closest approach	UK: /ˈdɪstəns əv ˈkləʊsɪst əˈprəʊtʃ/ US: /ˈdɪstəns əv ˈkloʊsəst əˈproʊtʃ/	The minimum separation reached in a head-on repulsive scattering event.
emission spectrum	UK: /ɪˈmɪʃən ˈspektrəm/ US: /ɪˈmɪʃən ˈspektrəm/	A spectrum of discrete wavelengths emitted by excited atoms.
absorption spectrum	UK: /əbˈzɔːpʃən ˈspektrəm/ US: /əbˈzɔːrpʃən ˈspektrəm/	A spectrum containing wavelengths removed by absorption.
energy level	UK: /ˈenədʒi ˈlevəl/ US: /ˈenɚdʒi ˈlevəl/	One of the discrete permitted energy eigenvalues of a bound quantum system in the model used.
atomic transition	UK: /əˈtɒmɪk trænˈzɪʃən/ US: /əˈtɑːmɪk trænˈzɪʃən/	A change between atomic energy levels, accompanied by absorption or emission of the corresponding energy.
photon	UK: /ˈfəʊtɒn/ US: /ˈfoʊˌtɑːn/	A quantum of electromagnetic radiation with energy $E=hf$ and momentum $p=h/\lambda$.
Bohr model	UK: /bɔː ˈmɒdəl/ US: /bɔːr ˈmɑːdəl/	An atomic model with electrons in permitted quantized orbits.
quantized angular momentum	UK: /ˈkwɒntaɪzd ˈænɡjʊlə məˈmentəm/ US: /ˈkwɑːntaɪzd ˈæŋɡjəlɚ moʊˈmentəm/	Angular momentum restricted to discrete permitted values.
nuclear radius	UK: /ˈnjuːklɪə ˈreɪdɪəs/ US: /ˈnuːkliɚ ˈreɪdiəs/	The effective radius of a nucleus.

E.2 Quantum physics

Term	Pronunciation	Definition
photoelectric effect	UK: /ˌfəʊtəʊɪˈlektrɪk ɪˈfekt/ US: /ˌfoʊtoʊɪˈlektrɪk ɪˈfekt/	The emission of electrons from a material after absorption of electromagnetic radiation.
photoelectron	UK: /ˌfəʊtəʊɪˈlektrɒn/ US: /ˌfoʊtoʊɪˈlektrɑːn/	An electron emitted by the photoelectric effect.
threshold frequency	UK: /ˈθreˌʃəʊld ˈfriːkwənsi/ US: /ˈθreˌʃoʊld ˈfriːkwənsi/	The minimum radiation frequency required to emit photoelectrons.
work function	UK: /wɜːk ˈfəŋkʃən/ US: /wɝːk ˈfʌŋkʃən/	The minimum energy required to remove an electron from the surface of a material.
maximum kinetic energy	UK: /ˈmæksɪməm kɪˈnetɪk ˈenədʒi/ US: /ˈmæksəməm kɪˈnetɪk ˈenɚdʒi/	The greatest kinetic energy among emitted photoelectrons.
stopping potential	UK: /ˈstɒpɪŋ pəˈtenʃəl/ US: /ˈstɑːpɪŋ pəˈtenʃəl/	The reverse potential difference required to stop the most energetic photoelectrons.
wave-particle duality	UK: /weɪv ˈpɑːtɪkəl djuːˈælɪti/ US: /weɪv ˈpɑːrtəkəl duˈæləti/	The quantum behaviour in which light and matter require both wave-like and particle-like descriptions, depending on the experiment.
matter wave	UK: /ˈmætə weɪv/ US: /ˈmætɚ weɪv/	The wave behaviour associated with a material particle.
de Broglie wavelength	UK: /də brɔɪ ˈweɪvleŋθ/ US: /də brɔɪ ˈweɪvleŋθ/	The wavelength associated with a particle of momentum p, given by λ = h/p.
particle diffraction	UK: /ˈpɑːtɪkəl dɪˈfrækʃən/ US: /ˈpɑːrtəkəl dɪˈfrækʃən/	Diffraction shown by particles when their wavelength is comparable to structural spacing.
Compton scattering	UK: /ˈkɒmptən ˈskætərɪŋ/ US: /ˈkɑːmptən ˈskætɚɪŋ/	Scattering of a photon by a particle, usually an electron, with a wavelength shift determined by the scattering angle.
wavelength shift	UK: /ˈweɪvˌleŋθ ʃɪft/ US: /ˈweɪvˌleŋθ ʃɪft/	The difference between final and initial photon wavelength.
classical wave theory	UK: /ˈklæsɪkəl weɪv ˈθɪəri/ US: /ˈklæsɪkəl weɪv ˈθɪri/	The non-quantized wave description of electromagnetic radiation.
Planck constant	UK: /plæŋk ˈkɒnstənt/ US: /plæŋk ˈkɑːnstənt/	The universal constant relating photon energy to frequency and wavelength to momentum.

E.3 Radioactive decay

Term	Pronunciation	Definition
isotope	UK: /ˈaɪsəˌtəʊp/ US: /ˈaɪsətoʊp/	One of two or more nuclides with the same proton number but different neutron numbers.
nuclide	UK: /ˈnjuːklaɪd/ US: /ˈnuːklaɪd/	A species of atom specified by its proton number and neutron number.
nuclear stability	UK: /ˈnjuːklɪə stəˈbɪlɪti/ US: /ˈnuːkliɚ stəˈbɪlɪti/	The tendency of a nucleus to remain unchanged rather than decay.
binding energy	UK: /ˈbaɪndɪŋ ˈenədʒi/ US: /ˈbaɪndɪŋ ˈenɚdʒi/	The positive energy required to separate a bound system into specified free constituents.
binding energy per nucleon	UK: /ˈbaɪndɪŋ ˈenədʒi pə ˈnjuːkliɒn/ US: /ˈbaɪndɪŋ ˈenɚdʒi pɚ ˈnuːkliɑːn/	The total binding energy of a nucleus divided by its nucleon number.
mass defect	UK: /mæs ˈdiːfekt/ US: /mæs ˈdiːfekt/	The sum of the rest masses of the separated constituent nucleons minus the rest mass of the bound nucleus.
mass-energy equivalence	UK: /mæs ˈenədʒi ɪˈkwɪvələns/ US: /mæs ˈenɚdʒi ɪˈkwɪvələns/	The equivalence of mass and energy expressed by E equals mc squared.
strong nuclear force	UK: /strɒŋ ˈnjuːklɪə fɔːs/ US: /strɔːŋ ˈnuːkliɚ fɔːrs/	The short-range interaction between nucleons that is attractive over typical nuclear separations and strongly repulsive at very small separations.
radioactive decay	UK: /ˌreɪdɪəʊˈæktɪv dɪˈkeɪ/ US: /ˌreɪdioʊˈæktɪv dɪˈkeɪ/	The spontaneous and random transformation of an unstable nucleus into another state or nuclide.
alpha decay	UK: /ˈælfə dɪˈkeɪ/ US: /ˈælfə dɪˈkeɪ/	Decay in which a nucleus emits an alpha particle.
beta-minus decay	UK: /ˈbiːtə ˈmaɪnəs dɪˈkeɪ/ US: /ˈbeɪtə ˈmaɪnəs dɪˈkeɪ/	Decay in which a neutron changes into a proton, electron and antineutrino.
beta-plus decay	UK: /ˈbiːtə pləs dɪˈkeɪ/ US: /ˈbeɪtə plʌs dɪˈkeɪ/	Decay in which a proton changes into a neutron, positron and neutrino.
gamma decay	UK: /ˈɡæmə dɪˈkeɪ/ US: /ˈɡæmə dɪˈkeɪ/	A nuclear transition that emits a gamma photon without changing nucleon or proton number.
positron	UK: /ˈpɒzɪtrɒn/ US: /ˈpɑːzɪtrɑːn/	The positively charged antiparticle of the electron.
neutrino	UK: /njuːˈtriːnəʊ/ US: /nuːˈtriːnoʊ/	An electrically neutral elementary particle with very small non-zero mass that participates in the weak interaction.
antineutrino	UK: /ˌæntinjuːˈtriːnəʊ/ US: /ˌæntinuːˈtriːnoʊ/	The antiparticle of the neutrino, electrically neutral and participating in the weak interaction.
ionizing power	UK: /ˈaɪənaɪzɪŋ ˈpaʊə/ US: /ˈaɪənaɪzɪŋ ˈpaʊɚ/	The ability of radiation to produce ions in matter.
penetrating power	UK: /ˈpenɪˌtreɪtɪŋ ˈpaʊə/ US: /ˈpenəˌtreɪtɪŋ ˈpaʊɚ/	The ability of radiation to pass through matter.
activity	UK: /ækˈtɪvɪti/ US: /ækˈtɪvəti/	The mean number of nuclear decays per unit time in a radioactive sample.
count rate	UK: /kaʊnt reɪt/ US: /kaʊnt reɪt/	The number of detector counts recorded per unit time.
background radiation	UK: /ˈbækˌɡraʊnd ˌreɪdɪˈeɪʃən/ US: /ˈbækˌɡraʊnd ˌreɪdiˈeɪʃən/	Ionizing radiation detected from environmental and instrumental sources other than the source being investigated.
half-life	UK: /hɑːf laɪf/ US: /hæf laɪf/	The time for the expected number of undecayed nuclei, or the activity of a large sample, to fall to half its initial value.
decay constant	UK: /dɪˈkeɪ ˈkɒnstənt/ US: /dɪˈkeɪ ˈkɑːnstənt/	The constant decay probability per unit time for an individual unstable nucleus in the exponential-decay model.
exponential decay	UK: /ˌekspəʊˈnenʃəl dɪˈkeɪ/ US: /ˌekspoʊˈnenʃəl dɪˈkeɪ/	Decay in which the rate is proportional to the number of undecayed nuclei.
continuous beta spectrum	UK: /kənˈtɪnjuːəs ˈbiːtə ˈspektrəm/ US: /kənˈtɪnjuəs ˈbeɪtə ˈspektrəm/	The continuous distribution of beta-particle energies.
discrete gamma spectrum	UK: /dɪˈskriːt ˈɡæmə ˈspektrəm/ US: /dɪˈskriːt ˈɡæmə ˈspektrəm/	A set of distinct gamma-ray energies from nuclear transitions.
neutron-to-proton ratio	UK: /ˈnjuːtrɒn tə ˈprəʊtɒn ˈreɪʃiəʊ/ US: /ˈnuːtrɑːn tuː ˈproʊtɑːn ˈreɪʃioʊ/	The ratio of neutron number to proton number in a nucleus.
becquerel	UK: /ˌbekəˈrel/ US: /ˌbekəˈrel/	The SI unit of activity equal to one decay per second.

E.4 Fission

Term	Pronunciation	Definition
nuclear fission	UK: /ˈnjuːklɪə ˈfɪʃən/ US: /ˈnuːkliɚ ˈfɪʃən/	The splitting of a heavy nucleus into two lighter nuclei, usually with neutrons and energy released.
spontaneous fission	UK: /spɒnˈteɪnɪəs ˈfɪʃən/ US: /spɑːnˈteɪniəs ˈfɪʃən/	Fission occurring without absorption of an incident neutron.
neutron-induced fission	UK: /ˈnjuːtrɒn ɪnˈdjuːst ˈfɪʃən/ US: /ˈnuːtrɑːn ɪnˈduːst ˈfɪʃən/	Fission initiated when a nucleus absorbs a neutron.
fission fragment	UK: /ˈfɪʃən ˈfræɡmənt/ US: /ˈfɪʃən ˈfræɡmənt/	One of the smaller nuclei produced in fission.
chain reaction	UK: /tʃeɪn rɪˈækʃən/ US: /tʃeɪn riˈækʃən/	A sequence in which neutrons released by one fission generation induce fissions in later generations.
criticality	UK: /ˌkrɪtɪˈkæləti/ US: /ˌkrɪtɪˈkæləti/	The state of a fission chain reaction: subcritical if it decreases, critical if it remains steady, and supercritical if it increases.
moderator	UK: /ˈmɒdəˌreɪtə/ US: /ˈmɑːdɚˌeɪtɚ/	A reactor material that slows neutrons, mainly by collisions, while absorbing relatively few of them.
control rod	UK: /kənˈtrəʊl rɒd/ US: /kənˈtroʊl rɑːd/	A neutron-absorbing reactor component inserted or withdrawn to control the fission rate.
heat exchanger	UK: /hiːt eksˈtʃeɪndʒə/ US: /hiːt ɪksˈtʃeɪndʒɚ/	A device that transfers thermal energy between fluids without mixing them.
shielding	UK: /ˈʃiːldɪŋ/ US: /ˈʃiːldɪŋ/	Material used to reduce exposure to ionizing radiation.
nuclear reactor	UK: /ˈnjuːklɪə rɪˈæktə/ US: /ˈnuːkliɚ riˈæktɚ/	A system in which a controlled fission chain reaction releases energy.
nuclear fuel	UK: /ˈnjuːklɪə ˈfjuːəl/ US: /ˈnuːkliɚ ˈfjuːəl/	A fissile material used to sustain fission in a reactor.
radioactive waste	UK: /ˌreɪdɪəʊˈæktɪv weɪst/ US: /ˌreɪdioʊˈæktɪv weɪst/	Radioactive material requiring controlled handling, storage or disposal.
energy release	UK: /ˈenədʒi rɪˈliːs/ US: /ˈenɚdʒi riˈliːs/	The difference between initial and final total rest energy appearing as kinetic energy, radiation or other transferred energy.

E.5 Fusion and stars

Term	Pronunciation	Definition
nuclear fusion	UK: /ˈnjuːklɪə ˈfjuːʒən/ US: /ˈnuːkliɚ ˈfjuːʒən/	A nuclear reaction in which light nuclei combine to form heavier nuclei, with energy released when the products have lower total rest mass.
stellar fusion	UK: /ˈstelə ˈfjuːʒən/ US: /ˈstelɚ ˈfjuːʒən/	Fusion reactions that supply energy inside stars.
radiation pressure	UK: /ˌreɪdɪˈeɪʃən ˈpreʃə/ US: /ˌreɪdiˈeɪʃən ˈpreʃɚ/	Pressure produced when electromagnetic radiation transfers momentum to matter.
gravitational force	UK: /ˌɡrævɪˈteɪʃənəl fɔːs/ US: /ˌɡrævɪˈteɪʃənəl fɔːrs/	The attractive force between masses; in a star it acts inward and is balanced by the pressure-gradient force in hydrostatic equilibrium.
hydrostatic equilibrium	UK: /ˌhaɪdrəˈstætɪk ˌiːkwɪˈlɪbrɪəm/ US: /ˌhaɪdroʊˈstætɪk ˌiːkwəˈlɪbriəm/	The state in which the outward pressure-gradient force balances inward gravity throughout a star.
stellar evolution	UK: /ˈstelə ˌiːvəˈluːʃən/ US: /ˈstelɚ ˌevəˈluːʃən/	The sequence of changes in a star over its lifetime.
protostar	UK: /ˈprəʊtəʊstɑː/ US: /ˈproʊtoʊstɑːr/	A forming star before sustained hydrogen fusion begins.
main sequence	UK: /meɪn ˈsiːkwəns/ US: /meɪn ˈsiːkwəns/	The band on the Hertzsprung–Russell diagram occupied by stars that sustain hydrogen fusion in their cores.
red giant	UK: /red ˈdʒaɪənt/ US: /red ˈdʒaɪənt/	A cool luminous evolved star with a large radius.
supergiant	UK: /ˈsuːpədʒaɪənt/ US: /ˈsuːpərdʒaɪənt/	An extremely luminous star with a very large radius.
white dwarf	UK: /waɪt dwɔːf/ US: /waɪt dwɔːrf/	A compact stellar remnant supported primarily by electron degeneracy pressure.
stellar remnant	UK: /ˈstelə ˈremnənt/ US: /ˈstelɚ ˈremnənt/	The compact object left after a star ends its active evolutionary stages.
Hertzsprung-Russell diagram	UK: /ˈhɜːtsprʊŋ ˈrʌsəl ˈdaɪəɡræm/ US: /ˈhɝːtsprʊŋ ˈrʌsəl ˈdaɪəɡræm/	A graph classifying stars by luminosity and surface temperature.
instability strip	UK: /ˌɪnstəˈbɪlɪti strɪp/ US: /ˌɪnstəˈbɪlɪti strɪp/	A region of the HR diagram containing pulsating variable stars.
surface temperature	UK: /ˈsɜːfɪs ˈtemprətʃə/ US: /ˈsɝːfəs ˈtemprətʃɚ/	The effective temperature characterizing radiation from a star’s surface.
stellar luminosity	UK: /ˈstelə ˌluːmɪˈnɒsɪti/ US: /ˈstelɚ ˌluːməˈnɑːsəti/	The total power emitted by a star.
stellar radius	UK: /ˈstelə ˈreɪdɪəs/ US: /ˈstelɚ ˈreɪdiəs/	The effective radius of a star.
stellar spectrum	UK: /ˈstelə ˈspektrəm/ US: /ˈstelɚ ˈspektrəm/	The distribution of a star’s emitted intensity with wavelength.
stellar parallax	UK: /ˈstelə ˈpærəlæks/ US: /ˈstelɚ ˈpærəlæks/	Half the apparent annual angular shift of a nearby star relative to distant background objects, as viewed from opposite sides of Earth’s orbit.
parsec	UK: /ˈpɑːsek/ US: /ˈpɑːrsek/	The distance at which one astronomical unit subtends an angle of one arcsecond, approximately 3.26 light-years.
light-year	UK: /laɪt jɪə/ US: /laɪt jɪr/	The distance travelled by light in vacuum in one year.
astronomical unit	UK: /ˌæstrəˈnɒmɪkəl ˈjuːnɪt/ US: /ˌæstrəˈnɑːmɪkəl ˈjuːnət/	A unit of length defined as exactly $149\,597\,870\,700\ \mathrm{m}$.
arcsecond	UK: /ˈɑːksekənd/ US: /ˈɑːrksekənd/	An angular unit equal to one three-thousand-six-hundredth of a degree.
element formation	UK: /ˈelɪmənt fɔːˈmeɪʃən/ US: /ˈeləmənt fɔːrˈmeɪʃən/	The production of chemical elements through nuclear reactions.

Mathematical terminology used in IB Physics

This section covers the mathematical terminology used in IB Physics for algebra, functions and graphs, geometry and trigonometry, vectors, calculus, statistics, data analysis and uncertainty. Some terms also appear earlier in specific physical contexts; here they are defined in their general mathematical sense.

Mathematical notation and operations

Term	Pronunciation	Definition
mathematical notation	UK: /ˌmæθəˈmætɪkəl nəʊˈteɪʃən/ US: /ˌmæθəˈmætɪkəl noʊˈteɪʃən/	A system of symbols and conventions used to represent mathematical quantities, operations and relations.
symbol	UK: /ˈsɪmbəl/ US: /ˈsɪmbəl/	A written sign used to represent a quantity, operation, relation or object.
equality	UK: /ɪˈkwɒləti/ US: /ɪˈkwɑːləti/	A statement that two mathematical expressions have the same value.
inequality	UK: /ˌɪnɪˈkwɒləti/ US: /ˌɪnɪˈkwɑːləti/	A statement comparing two expressions using relations such as greater than or less than.
plus sign	UK: /ˈplʌs saɪn/ US: /ˈplʌs saɪn/	The symbol $+$, used for addition or to indicate a positive value.
minus sign	UK: /ˈmaɪnəs saɪn/ US: /ˈmaɪnəs saɪn/	The symbol $-$, used for subtraction, a negative value or an opposite direction.
multiplication	UK: /ˌmʌltɪplɪˈkeɪʃən/ US: /ˌmʌltəpləˈkeɪʃən/	The operation of combining factors to obtain a product.
division	UK: /dɪˈvɪʒən/ US: /dɪˈvɪʒən/	The operation of finding how many times one quantity is contained in another, or forming a quotient.
sum	UK: /sʌm/ US: /sʌm/	The result of addition, or a quantity formed by adding terms.
difference	UK: /ˈdɪfrəns/ US: /ˈdɪfrəns/	The result obtained by subtracting one quantity from another.
product	UK: /ˈprɒdʌkt/ US: /ˈprɑːdʌkt/	The result of multiplication.
quotient	UK: /ˈkwəʊʃənt/ US: /ˈkwoʊʃənt/	The result of division.
absolute value	UK: /ˈæbsəluːt ˈvæljuː/ US: /ˈæbsəluːt ˈvæljuː/	The non-negative distance of a real number from zero, written $\lvert x\rvert$.
change in	UK: /ˈtʃeɪndʒ ɪn/ US: /ˈtʃeɪndʒ ɪn/	The final value minus the initial value, commonly represented by the symbol $\Delta$.
ratio	UK: /ˈreɪʃiəʊ/ US: /ˈreɪʃioʊ/	A comparison of two quantities by division.
fraction	UK: /ˈfrækʃən/ US: /ˈfrækʃən/	A number or algebraic expression written as one quantity divided by another non-zero quantity.
numerator	UK: /ˈnjuːməreɪtə/ US: /ˈnuːməreɪtər/	The quantity written above the fraction bar.
denominator	UK: /dɪˈnɒmɪneɪtə/ US: /dɪˈnɑːməneɪtər/	The non-zero quantity written below the fraction bar.
decimal	UK: /ˈdesɪməl/ US: /ˈdesəməl/	A representation of a number using powers of ten and a decimal point.
percentage	UK: /pəˈsentɪdʒ/ US: /pərˈsentɪdʒ/	A ratio expressed as a number of parts per hundred.
summation notation	UK: /sʌˈmeɪʃən nəʊˈteɪʃən/ US: /sʌˈmeɪʃən noʊˈteɪʃən/	Compact notation using the sigma symbol $\Sigma$ to represent the sum of a sequence of terms.
subscript	UK: /ˈsʌbskrɪpt/ US: /ˈsʌbskrɪpt/	A smaller symbol written below and to the right of another symbol, often used as a label or index.
superscript	UK: /ˈsuːpəskrɪpt/ US: /ˈsuːpərskrɪpt/	A smaller symbol written above and to the right of another symbol, often used as an exponent.

Algebra and proportionality

Term	Pronunciation	Definition
number	UK: /ˈnʌmbə/ US: /ˈnʌmbər/	A mathematical object used to count, measure or label quantities.
integer	UK: /ˈɪntɪdʒə/ US: /ˈɪntədʒər/	A whole number that may be positive, negative or zero.
positive number	UK: /ˈpɒzətɪv ˈnʌmbə/ US: /ˈpɑːzətɪv ˈnʌmbər/	A real number greater than zero.
negative number	UK: /ˈneɡətɪv ˈnʌmbə/ US: /ˈneɡətɪv ˈnʌmbər/	A real number less than zero.
variable	UK: /ˈveəriəbəl/ US: /ˈveriəbəl/	A symbol representing a quantity whose value may vary or be unknown.
constant	UK: /ˈkɒnstənt/ US: /ˈkɑːnstənt/	A quantity whose value is fixed within the context being considered.
coefficient	UK: /ˌkəʊɪˈfɪʃənt/ US: /ˌkoʊəˈfɪʃənt/	A numerical or algebraic factor multiplying a term.
term	UK: /tɜːm/ US: /tɝːm/	A single part of an expression separated from other parts by addition or subtraction.
expression	UK: /ɪkˈspreʃən/ US: /ɪkˈspreʃən/	A mathematical combination of numbers, variables and operations that does not assert an equality.
equation	UK: /ɪˈkweɪʒən/ US: /ɪˈkweɪʒən/	A statement that two mathematical expressions are equal.
formula	UK: /ˈfɔːmjələ/ US: /ˈfɔːrmjələ/	An equation expressing a general relationship between quantities.
identity	UK: /aɪˈdentɪti/ US: /aɪˈdentəti/	An equality that is true for every permitted value of its variables.
subject of a formula	UK: /ˈsʌbdʒɪkt əv ə ˈfɔːmjələ/ US: /ˈsʌbdʒɪkt əv ə ˈfɔːrmjələ/	The variable isolated on one side of a formula.
rearrangement	UK: /ˌriːəˈreɪndʒmənt/ US: /ˌriːəˈreɪndʒmənt/	An algebraic transformation that changes the form of an equation while preserving its solutions.
substitution	UK: /ˌsʌbstɪˈtjuːʃən/ US: /ˌsʌbstəˈtuːʃən/	The replacement of a symbol by a numerical value or an equivalent expression.
solution	UK: /səˈluːʃən/ US: /səˈluːʃən/	A value or set of values that satisfies an equation or system of equations.
simultaneous equations	UK: /ˌsɪməlˈteɪniəs ɪˈkweɪʒənz/ US: /ˌsaɪməlˈteɪniəs ɪˈkweɪʒənz/	Two or more equations whose common solution must satisfy all equations at the same time.
proportion	UK: /prəˈpɔːʃən/ US: /prəˈpɔːrʃən/	A relationship in which one ratio is equal to another, or one quantity varies in a specified way with another.
directly proportional	UK: /daɪˈrektli prəˈpɔːʃənəl/ US: /dəˈrektli prəˈpɔːrʃənəl/	Related so that the ratio of the dependent quantity to the independent quantity is constant: $y=kx$.
inversely proportional	UK: /ɪnˈvɜːsli prəˈpɔːʃənəl/ US: /ɪnˈvɝːsli prəˈpɔːrʃənəl/	Related so that the product of the two quantities is constant: $y=k/x$.
exponent	UK: /ɪkˈspəʊnənt/ US: /ɪkˈspoʊnənt/	The number or expression indicating the power to which a base is raised.
power	UK: /ˈpaʊə/ US: /ˈpaʊər/	An expression formed by raising a base to an exponent, such as $x^n$.
square	UK: /skweə/ US: /skwer/	The second power of a quantity: $x^2$.
square root	UK: /skweə ruːt/ US: /skwer ruːt/	A number that, when squared, gives the original number.
cube	UK: /kjuːb/ US: /kjuːb/	The third power of a quantity: $x^3$.
cube root	UK: /kjuːb ruːt/ US: /kjuːb ruːt/	A number that, when cubed, gives the original number.
reciprocal	UK: /rɪˈsɪprəkəl/ US: /rɪˈsɪprəkəl/	The multiplicative inverse of a non-zero number $x$, equal to $1/x$.
scientific notation	UK: /ˌsaɪənˈtɪfɪk nəʊˈteɪʃən/ US: /ˌsaɪənˈtɪfɪk noʊˈteɪʃən/	A representation of a number in the form $a\times10^n$, where $1\leq\lvert a\rvert<10$ and $n$ is an integer.
standard form	UK: /ˈstændəd fɔːm/ US: /ˈstændərd fɔːrm/	The British mathematical term commonly used for scientific notation.
order of magnitude	UK: /ˌɔːdər əv ˈmæɡnɪtjuːd/ US: /ˌɔːrdər əv ˈmæɡnətuːd/	The power of ten that characterizes the approximate scale of a quantity.
logarithm	UK: /ˈlɒɡərɪðəm/ US: /ˈlɔːɡərɪðəm/	The exponent to which a specified base must be raised to obtain a given number.
natural logarithm	UK: /ˈnætʃərəl ˈlɒɡərɪðəm/ US: /ˈnætʃərəl ˈlɔːɡərɪðəm/	A logarithm with base $e$, written $\ln x$.
exponential function	UK: /ˌekspəˈnenʃəl ˈfʌŋkʃən/ US: /ˌekspəˈnenʃəl ˈfʌŋkʃən/	A function in which the variable occurs in the exponent, such as $y=Ae^{kx}$.

Functions and graphs

Term	Pronunciation	Definition
function	UK: /ˈfʌŋkʃən/ US: /ˈfʌŋkʃən/	A rule that assigns exactly one output value to each permitted input value.
independent variable	UK: /ˌɪndɪˈpendənt ˈveəriəbəl/ US: /ˌɪndɪˈpendənt ˈveriəbəl/	The input variable that is selected, controlled or placed on the horizontal axis.
dependent variable	UK: /dɪˈpendənt ˈveəriəbəl/ US: /dɪˈpendənt ˈveriəbəl/	The output variable whose value depends on the independent variable.
coordinate	UK: /kəʊˈɔːdɪnət/ US: /koʊˈɔːrdənət/	A number, or one of a set of numbers, specifying the position of a point.
origin	UK: /ˈɒrɪdʒɪn/ US: /ˈɔːrədʒɪn/	The point at which the coordinate axes intersect and all coordinates are zero.
axis	UK: /ˈæksɪs/ US: /ˈæksɪs/	A reference line on a graph or coordinate system along which values are measured.
horizontal axis	UK: /ˌhɒrɪˈzɒntəl ˈæksɪs/ US: /ˌhɔːrəˈzɑːntəl ˈæksɪs/	The left-to-right axis of a graph, commonly used for the independent variable.
vertical axis	UK: /ˈvɜːtɪkəl ˈæksɪs/ US: /ˈvɝːtɪkəl ˈæksɪs/	The bottom-to-top axis of a graph, commonly used for the dependent variable.
axis scale	UK: /ˈæksɪs skeɪl/ US: /ˈæksɪs skeɪl/	The numerical spacing and range used to represent values along an axis.
graph	UK: /ɡrɑːf/ US: /ɡræf/	A visual representation of the relationship between variables.
plot	UK: /plɒt/ US: /plɑːt/	A graph or the act of marking data points on a graph.
data point	UK: /ˈdeɪtə pɔɪnt/ US: /ˈdeɪtə pɔɪnt/	A plotted point representing one pair or set of measured values.
curve	UK: /kɜːv/ US: /kɝːv/	A continuous line representing a relationship that need not be linear.
straight line	UK: /streɪt laɪn/ US: /streɪt laɪn/	A line with constant gradient.
linear relationship	UK: /ˈlɪniə rɪˈleɪʃənʃɪp/ US: /ˈlɪniər riˈleɪʃənʃɪp/	A relationship represented by a straight-line graph, generally written $y=mx+c$.
inverse-square relationship	UK: /ˌɪnvɜːs ˈskweə rɪˈleɪʃənʃɪp/ US: /ˌɪnvɝːs ˈskwer riˈleɪʃənʃɪp/	A relationship of the form $y=k/x^2$.
gradient	UK: /ˈɡreɪdiənt/ US: /ˈɡreɪdiənt/	The change in the vertical coordinate divided by the corresponding change in the horizontal coordinate.
slope	UK: /sləʊp/ US: /sloʊp/	A synonym for gradient, particularly common in American English.
intercept	UK: /ˈɪntəsept/ US: /ˈɪntərsept/	The coordinate at which a graph crosses an axis.
tangent to a curve	UK: /ˈtændʒənt tə ə kɜːv/ US: /ˈtændʒənt tə ə kɝːv/	A straight line that has the same local gradient as a curve at the point of contact.
secant line	UK: /ˈsiːkənt laɪn/ US: /ˈsiːkənt laɪn/	A straight line passing through two distinct points on a curve.
maximum	UK: /ˈmæksɪməm/ US: /ˈmæksɪməm/	The greatest value of a quantity within a specified domain or interval.
minimum	UK: /ˈmɪnɪməm/ US: /ˈmɪnɪməm/	The least value of a quantity within a specified domain or interval.
turning point	UK: /ˈtɜːnɪŋ pɔɪnt/ US: /ˈtɝːnɪŋ pɔɪnt/	A point at which a curve changes from increasing to decreasing or from decreasing to increasing.
asymptote	UK: /ˈæsɪmtəʊt/ US: /ˈæsɪmtoʊt/	A line that a curve approaches arbitrarily closely in a limiting region.
interpolation	UK: /ɪnˌtɜːpəˈleɪʃən/ US: /ɪnˌtɝːpəˈleɪʃən/	Estimation of a value within the range of measured data.
extrapolation	UK: /ɪkˌstræpəˈleɪʃən/ US: /ɪkˌstræpəˈleɪʃən/	Estimation of a value outside the range of measured data.
linearization	UK: /ˌlɪniəraɪˈzeɪʃən/ US: /ˌlɪniərəˈzeɪʃən/	A transformation of variables that converts a non-linear relationship into a linear one.
logarithmic scale	UK: /ˌlɒɡəˈrɪðmɪk skeɪl/ US: /ˌlɔːɡəˈrɪðmɪk skeɪl/	A scale on which equal distances represent equal ratios rather than equal differences.
best-fit line	UK: /ˌbest ˈfɪt laɪn/ US: /ˌbest ˈfɪt laɪn/	A line chosen to represent the overall trend of a set of data points.
residual	UK: /rɪˈzɪdjuəl/ US: /rɪˈzɪdʒuəl/	The observed value minus the value predicted by a fitted model.

Geometry and trigonometry

Term	Pronunciation	Definition
angle	UK: /ˈæŋɡəl/ US: /ˈæŋɡəl/	The amount of rotation between two intersecting lines or directions.
degree	UK: /dɪˈɡriː/ US: /dɪˈɡriː/	An angular unit equal to one three-hundred-and-sixtieth of a complete revolution.
radian	UK: /ˈreɪdiən/ US: /ˈreɪdiən/	The SI-derived angular unit; one radian subtends an arc whose length equals the radius.
arc	UK: /ɑːk/ US: /ɑːrk/	A portion of the circumference of a circle.
arc length	UK: /ɑːk leŋθ/ US: /ɑːrk leŋθ/	The distance measured along a circular arc, equal to $s=r\theta$ when $\theta$ is in radians.
circumference	UK: /səˈkʌmfərəns/ US: /sərˈkʌmfərəns/	The perimeter of a circle, equal to $2\pi r$.
radius	UK: /ˈreɪdiəs/ US: /ˈreɪdiəs/	The distance from the centre of a circle or sphere to its boundary.
diameter	UK: /daɪˈæmɪtə/ US: /daɪˈæmətər/	A straight line through the centre of a circle or sphere joining two boundary points; its length is $2r$.
perimeter	UK: /pəˈrɪmɪtə/ US: /pəˈrɪmətər/	The total length of the boundary of a plane shape.
area	UK: /ˈeəriə/ US: /ˈeriə/	The measure of the extent of a two-dimensional region.
surface area	UK: /ˈsɜːfɪs ˈeəriə/ US: /ˈsɝːfəs ˈeriə/	The total area of the outer surface of a three-dimensional object.
cross-sectional area	UK: /ˌkrɒs ˈsekʃənəl ˈeəriə/ US: /ˌkrɔːs ˈsekʃənəl ˈeriə/	The area of a section formed by cutting an object with a plane.
volume	UK: /ˈvɒljuːm/ US: /ˈvɑːljuːm/	The measure of the three-dimensional space occupied by an object or region.
right-angled triangle	UK: /ˌraɪt æŋɡəld ˈtraɪæŋɡəl/ US: /ˌraɪt ˈtraɪæŋɡəl/	A triangle containing one angle of $90^\circ$; American English commonly uses right triangle.
hypotenuse	UK: /haɪˈpɒtənjuːs/ US: /haɪˈpɑːtənuːs/	The side opposite the right angle in a right-angled triangle.
adjacent side	UK: /əˈdʒeɪsənt saɪd/ US: /əˈdʒeɪsənt saɪd/	Relative to a chosen acute angle, the non-hypotenuse side that touches that angle.
opposite side	UK: /ˈɒpəzɪt saɪd/ US: /ˈɑːpəzət saɪd/	Relative to a chosen angle, the side lying across from that angle.
sine	UK: /saɪn/ US: /saɪn/	For an acute angle in a right-angled triangle, the ratio of opposite side to hypotenuse.
cosine	UK: /ˈkəʊsaɪn/ US: /ˈkoʊsaɪn/	For an acute angle in a right-angled triangle, the ratio of adjacent side to hypotenuse.
tangent function	UK: /ˈtændʒənt ˈfʌŋkʃən/ US: /ˈtændʒənt ˈfʌŋkʃən/	The trigonometric function defined by $\tan\theta=\sin\theta/\cos\theta$; in a right-angled triangle it is opposite divided by adjacent.
inverse sine	UK: /ˌɪnvɜːs ˈsaɪn/ US: /ˌɪnvɝːs ˈsaɪn/	The inverse function of sine on a restricted domain, used to determine an angle from its sine.
inverse cosine	UK: /ˌɪnvɜːs ˈkəʊsaɪn/ US: /ˌɪnvɝːs ˈkoʊsaɪn/	The inverse function of cosine on a restricted domain, used to determine an angle from its cosine.
inverse tangent	UK: /ˌɪnvɜːs ˈtændʒənt/ US: /ˌɪnvɝːs ˈtændʒənt/	The inverse function of tangent on a restricted domain, used to determine an angle from its tangent.
Pythagorean theorem	UK: /paɪˌθæɡəˈriːən ˈθɪərəm/ US: /paɪˌθæɡəˈriːən ˈθɪrəm/	The theorem that $a^2+b^2=c^2$ for a right-angled triangle with hypotenuse $c$.
similar triangles	UK: /ˈsɪmɪlə ˈtraɪæŋɡəlz/ US: /ˈsɪmələr ˈtraɪæŋɡəlz/	Triangles with equal corresponding angles and proportional corresponding sides.
parallel	UK: /ˈpærəlel/ US: /ˈpærəlel/	Describing lines, planes or vectors that have the same direction and do not intersect when extended.
perpendicular	UK: /ˌpɜːpənˈdɪkjələ/ US: /ˌpɝːpənˈdɪkjələr/	Meeting or oriented at a right angle.
normal	UK: /ˈnɔːməl/ US: /ˈnɔːrməl/	A line or direction perpendicular to a surface or curve at a specified point.

Vectors

Term	Pronunciation	Definition
scalar	UK: /ˈskeɪlə/ US: /ˈskeɪlər/	A quantity specified by magnitude only.
vector	UK: /ˈvektə/ US: /ˈvektər/	A quantity specified by both magnitude and direction.
magnitude	UK: /ˈmæɡnɪtjuːd/ US: /ˈmæɡnətuːd/	The non-negative size or length of a vector.
direction	UK: /dəˈrekʃən/ US: /dəˈrekʃən/	The orientation in which a vector points.
component	UK: /kəmˈpəʊnənt/ US: /kəmˈpoʊnənt/	The projection of a vector along a chosen direction or axis.
horizontal component	UK: /ˌhɒrɪˈzɒntəl kəmˈpəʊnənt/ US: /ˌhɔːrəˈzɑːntəl kəmˈpoʊnənt/	The component of a vector along the horizontal axis.
vertical component	UK: /ˈvɜːtɪkəl kəmˈpəʊnənt/ US: /ˈvɝːtɪkəl kəmˈpoʊnənt/	The component of a vector along the vertical axis.
vector addition	UK: /ˈvektə əˈdɪʃən/ US: /ˈvektər əˈdɪʃən/	The operation of combining vectors to obtain their resultant.
vector subtraction	UK: /ˈvektə səbˈtrækʃən/ US: /ˈvektər səbˈtrækʃən/	The addition of the negative of one vector to another vector.
resultant vector	UK: /rɪˈzʌltənt ˈvektə/ US: /rɪˈzʌltənt ˈvektər/	The single vector equal to the vector sum of two or more vectors.
resolution of a vector	UK: /ˌrezəˈluːʃən əv ə ˈvektə/ US: /ˌrezəˈluːʃən əv ə ˈvektər/	The process of expressing a vector as components along chosen directions.
unit vector	UK: /ˈjuːnɪt ˈvektə/ US: /ˈjuːnət ˈvektər/	A vector of magnitude one used to specify a direction.
scalar product	UK: /ˈskeɪlə ˈprɒdʌkt/ US: /ˈskeɪlər ˈprɑːdʌkt/	The scalar operation $\boldsymbol{a}\cdot\boldsymbol{b}=ab\cos\theta$.
vector diagram	UK: /ˈvektə ˈdaɪəɡræm/ US: /ˈvektər ˈdaɪəɡræm/	A diagram in which directed line segments represent vectors to scale or schematically.
head-to-tail method	UK: /ˌhed tə ˈteɪl ˈmeθəd/ US: /ˌhed tə ˈteɪl ˈmeθəd/	A graphical method of vector addition in which the tail of each vector is placed at the head of the preceding vector.
parallelogram method	UK: /ˌpærəˈleləɡræm ˈmeθəd/ US: /ˌpærəˈleləɡræm ˈmeθəd/	A graphical method in which two vectors form adjacent sides of a parallelogram and the diagonal gives the resultant.

Calculus

Term	Pronunciation	Definition
limit	UK: /ˈlɪmɪt/ US: /ˈlɪmɪt/	The value that a function or sequence approaches as its input approaches a specified value.
derivative	UK: /dɪˈrɪvətɪv/ US: /dɪˈrɪvətɪv/	The instantaneous rate of change of a function with respect to its variable.
differentiation	UK: /ˌdɪfərenʃiˈeɪʃən/ US: /ˌdɪfərenʃiˈeɪʃən/	The process of finding a derivative.
rate of change	UK: /reɪt əv tʃeɪndʒ/ US: /reɪt əv tʃeɪndʒ/	The change in one quantity divided by the corresponding change in another quantity.
instantaneous rate of change	UK: /ˌɪnstənˈteɪniəs reɪt əv tʃeɪndʒ/ US: /ˌɪnstənˈteɪniəs reɪt əv tʃeɪndʒ/	The limiting rate of change at one point, represented by a derivative.
differential	UK: /ˌdɪfəˈrenʃəl/ US: /ˌdɪfəˈrenʃəl/	A notation such as $\mathrm{d}x$ representing an infinitesimal change in a variable within calculus.
finite difference	UK: /ˌfaɪnaɪt ˈdɪfrəns/ US: /ˌfaɪnaɪt ˈdɪfrəns/	A difference such as $\Delta x$ between two distinct finite values.
integral	UK: /ˈɪntɪɡrəl/ US: /ˈɪntəɡrəl/	A mathematical quantity representing accumulation; a definite integral gives a signed accumulated total over an interval.
integration	UK: /ˌɪntɪˈɡreɪʃən/ US: /ˌɪntəˈɡreɪʃən/	The process of evaluating an integral.
definite integral	UK: /ˌdefɪnət ˈɪntɪɡrəl/ US: /ˌdefɪnət ˈɪntəɡrəl/	An integral evaluated between specified lower and upper limits.
area under a curve	UK: /ˈeəriə ˌʌndər ə kɜːv/ US: /ˈeriə ˌʌndər ə kɝːv/	The signed area between a graph and its horizontal axis over a specified interval, represented by a definite integral.

Statistics, data and uncertainty

Term	Pronunciation	Definition
data	UK: /ˈdeɪtə/ US: /ˈdeɪtə/	Recorded observations or measurements used for analysis.
data set	UK: /ˈdeɪtə set/ US: /ˈdeɪtə set/	A collection of related data values.
sample	UK: /ˈsɑːmpəl/ US: /ˈsæmpəl/	A subset of observations selected from a larger population.
population	UK: /ˌpɒpjəˈleɪʃən/ US: /ˌpɑːpjəˈleɪʃən/	The complete set of objects, events or measurements about which an inference is made.
probability	UK: /ˌprɒbəˈbɪləti/ US: /ˌprɑːbəˈbɪləti/	A number from zero to one that quantifies the likelihood of an event.
distribution	UK: /ˌdɪstrɪˈbjuːʃən/ US: /ˌdɪstrəˈbjuːʃən/	A description of how data values or probabilities are spread over possible outcomes.
normal distribution	UK: /ˌnɔːməl dɪstrɪˈbjuːʃən/ US: /ˌnɔːrməl dɪstrəˈbjuːʃən/	A symmetric bell-shaped probability distribution determined by its mean and standard deviation.
mean	UK: /miːn/ US: /miːn/	The arithmetic average, found by dividing the sum of values by the number of values.
arithmetic mean	UK: /ˌærɪθˈmetɪk miːn/ US: /ˌerɪθˈmetɪk miːn/	The sum of all values divided by the number of values.
median	UK: /ˈmiːdiən/ US: /ˈmiːdiən/	The middle value of an ordered data set, or the mean of the two middle values when the number of values is even.
mode	UK: /məʊd/ US: /moʊd/	The value occurring most frequently in a data set.
range	UK: /reɪndʒ/ US: /reɪndʒ/	The maximum value minus the minimum value in a data set.
variance	UK: /ˈveəriəns/ US: /ˈveriəns/	The mean squared deviation of values from their mean, with the precise divisor depending on whether a population or sample variance is used.
standard deviation	UK: /ˌstændəd ˌdiːviˈeɪʃən/ US: /ˌstændərd ˌdiːviˈeɪʃən/	The square root of the variance, measuring the spread of data around the mean.
uncertainty	UK: /ʌnˈsɜːtənti/ US: /ʌnˈsɝːtənti/	A quantified interval or parameter expressing the range within which a measured value is reasonably expected to lie.
absolute uncertainty	UK: /ˈæbsəluːt ʌnˈsɜːtənti/ US: /ˈæbsəluːt ʌnˈsɝːtənti/	An uncertainty expressed in the same units as the measured quantity.
fractional uncertainty	UK: /ˈfrækʃənəl ʌnˈsɜːtənti/ US: /ˈfrækʃənəl ʌnˈsɝːtənti/	The absolute uncertainty divided by the measured value.
percentage uncertainty	UK: /pəˈsentɪdʒ ʌnˈsɜːtənti/ US: /pərˈsentɪdʒ ʌnˈsɝːtənti/	The fractional uncertainty multiplied by $100\%$.
random uncertainty	UK: /ˈrændəm ʌnˈsɜːtənti/ US: /ˈrændəm ʌnˈsɝːtənti/	Uncertainty associated with unpredictable variations that cause repeated measurements to scatter.
systematic error	UK: /ˌsɪstəˈmætɪk ˈerə/ US: /ˌsɪstəˈmætɪk ˈerər/	A consistent bias that shifts measurements in the same general direction and is not removed by simple repetition.
accuracy	UK: /ˈækjərəsi/ US: /ˈækjərəsi/	The degree of agreement between a measured result and an accepted or reference value.
precision	UK: /prɪˈsɪʒən/ US: /prɪˈsɪʒən/	The degree of agreement among repeated measurements, or the fineness with which a value is resolved.
significant figures	UK: /sɪɡˌnɪfɪkənt ˈfɪɡəz/ US: /sɪɡˌnɪfɪkənt ˈfɪɡjərz/	Digits retained in a number to communicate its measured or calculated precision.
decimal places	UK: /ˈdesɪməl ˈpleɪsɪz/ US: /ˈdesəməl ˈpleɪsɪz/	The number of digits written to the right of the decimal point.
error bar	UK: /ˈerə bɑː/ US: /ˈerər bɑːr/	A graphical line showing the uncertainty interval associated with a plotted value.
upper bound	UK: /ˈʌpə baʊnd/ US: /ˈʌpər baʊnd/	The greatest value permitted by a stated interval or uncertainty.
lower bound	UK: /ˈləʊə baʊnd/ US: /ˈloʊər baʊnd/	The least value permitted by a stated interval or uncertainty.
percentage difference	UK: /pəˈsentɪdʒ ˈdɪfrəns/ US: /pərˈsentɪdʒ ˈdɪfrəns/	The absolute difference between two experimental values divided by their mean, multiplied by $100\%$.
percentage error	UK: /pəˈsentɪdʒ ˈerə/ US: /pərˈsentɪdʒ ˈerər/	The absolute difference between an experimental value and an accepted value divided by the accepted value, multiplied by $100\%$.
correlation	UK: /ˌkɒrəˈleɪʃən/ US: /ˌkɔːrəˈleɪʃən/	A statistical association between two variables; correlation alone does not establish causation.
positive correlation	UK: /ˈpɒzətɪv ˌkɒrəˈleɪʃən/ US: /ˈpɑːzətɪv ˌkɔːrəˈleɪʃən/	A relationship in which larger values of one variable tend to be associated with larger values of another.
negative correlation	UK: /ˈneɡətɪv ˌkɒrəˈleɪʃən/ US: /ˈneɡətɪv ˌkɔːrəˈleɪʃən/	A relationship in which larger values of one variable tend to be associated with smaller values of another.
linear regression	UK: /ˈlɪniə rɪˈɡreʃən/ US: /ˈlɪniər rɪˈɡreʃən/	A statistical method for fitting a straight-line model to data.
uncertainty in the gradient	UK: /ʌnˈsɜːtənti ɪn ðə ˈɡreɪdiənt/ US: /ʌnˈsɝːtənti ɪn ðə ˈɡreɪdiənt/	An estimate of the range of plausible gradient values consistent with the data and their uncertainties.
uncertainty in the intercept	UK: /ʌnˈsɜːtənti ɪn ði ˈɪntəsept/ US: /ʌnˈsɝːtənti ɪn ði ˈɪntərsept/	An estimate of the range of plausible intercept values consistent with the data and their uncertainties.
outlier	UK: /ˈaʊtlaɪə/ US: /ˈaʊtlaɪər/	A data value lying unusually far from the general pattern of the remaining data.

References

1. International Baccalaureate Organization, Physics guide, first assessment 2025.
2. International Baccalaureate Organization, Physics data booklet, first assessment 2025, version 1.2.
3. Cambridge University Press, Cambridge English Dictionary and Cambridge English Pronouncing Dictionary.
4. Oxford University Press, Oxford Learner’s Dictionaries and Oxford pronunciation resources.
5. Carnegie Mellon University, CMU Pronouncing Dictionary.
6. Open Speech and Language Resources, BEEP Dictionary; Britfone British English pronunciation lexicon.

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