The rearrangement of charges in a material caused by a nearby charged object, without direct contact.

An AC generator is a device that produces alternating current by rotating a coil in a magnetic field.

Acceleration is defined as the rate of change of velocity.

How close a measurement is to the true or accepted value.

Air resistance is the frictional force acting on objects moving through air.

An electric current that repeatedly reverses direction, typically produced by generators in power stations.

An electric current that repeatedly changes direction, typically produced by a generator.

A device used to measure electric current in a circuit.

The maximum displacement from equilibrium (or, for sound, the maximum pressure variation) of the oscillation.

A small rocky body that orbits the Sun, most commonly found in the asteroid belt between Mars and Jupiter.

Atmospheric pressure is the pressure exerted by the weight of the air above a surface.

The smallest unit of an element that retains the element’s chemical properties; it consists of a nucleus (protons and neutrons) with electrons around it.

The range of frequencies that a typical human can hear, about 20 Hz to 20 kHz.

An aurora is a natural light display caused by charged particles interacting with Earth’s atmosphere.

The ionizing radiation we are exposed to all the time from natural and human-made sources in our environment.

A model of the universe in which space has been expanding from a very hot, very dense early state, leading to the cooler, structured universe observed today.

An object with such strong gravity that, within a boundary called the event horizon, not even light can escape.

Boyle’s law states that pressure is inversely proportional to volume at constant temperature.

Describes a solid that breaks or shatters when deformed, with little permanent bending.

The random jittery motion of small visible particles (like smoke or pollen) caused by countless random collisions with much smaller molecules in a gas or liquid.

A cell is a device that provides electrical energy to a circuit.

A chain reaction is a self-sustaining sequence of nuclear fission events caused by neutrons released from previous fissions.

A physical change in which a substance transitions between solid, liquid, and gas due to energy transfer, without changing its chemical identity.

A property of matter that causes electric forces; like charges repel and opposite charges attract. The SI unit is the coulomb (C).

Energy stored in the bonds between atoms in molecules, which can be released or absorbed during chemical reactions.

A compass is a device that uses a magnetised needle to show direction using Earth’s magnetic field.

A method of storing energy by using surplus electricity to compress air into a cavern or vessel, then releasing it later to drive a turbine and generate electricity.

Compression is a pushing force in a squashed object.

A compression is a region in a longitudinal wave where the particles of the medium are close together, resulting in a high-pressure area.

Conduction is the transfer of heat through particle collisions.

Heat transfer through direct contact with objects or surfaces. Heat is either lost to or gained from the object based on temperature differences.

Heat transfer through direct contact with objects or surfaces. Heat is either lost to or gained from the object based on temperature differences.

Heat transfer through direct contact with objects or surfaces. Heat is either lost to or gained from the object based on temperature differences.

A material in which electrons can move easily through the material.

Energy cannot be created or destroyed. It can only be converted from one form to another.

A constellation is a recognized pattern of stars as seen from Earth.

Constructive interference is a phenomenon where two or more waves meet and combine to form a single new wave with a larger amplitude than the individual waves

Convection is the transfer of thermal energy through the movement of fluid particles, driven by differences in density.

The direction of current defined as the flow of positive charge; it is opposite to the direction electrons actually move in metal wires.

Electromagnetic radiation filling space, observed today mainly as microwaves, interpreted as cooled and stretched light released when the early universe became transparent.

A name given to the unknown cause of the observed acceleration of the universe’s expansion.

A logarithmic unit used to express sound level. An increase of 10 dB corresponds to a tenfold increase in sound intensity.

Density is the amount of mass per unit volume of a substance.

The variable that is measured; it may change in response to the independent variable.

Interference in which two waves combine to produce a smaller amplitude (and therefore reduced intensity), often when they are out of phase.

A thin, flexible surface that vibrates to create or detect sound waves.

Diffraction is the spreading out of waves when they pass through a gap or around an obstacle.

Reflection from a rough surface in which reflected rays scatter in many directions, so no distinct image is formed.

An electric current that flows in one direction only, typically supplied by batteries.

An electric current that flows in one direction only, typically produced by a constant voltage source such as a battery.

The Doppler effect is the change in observed wavelength or frequency of a wave due to relative motion between the source and the observer.

Describes a material that can be stretched into a wire without breaking.

A solar-system object that orbits the Sun and is nearly round due to its own gravity, but has not cleared the neighborhood around its orbit.

Efficiency is the proportion of input energy transferred into useful output energy.

A property of matter that can be positive or negative and causes electrical interactions (attraction or repulsion) between objects.

An electric circuit is a complete, closed path that allows electric current to flow.

Electric current is the flow of electric charge through a conductor.

Electric current is the rate at which electric charge flows through a conductor.

An electric field is a region around a charged object where another charge experiences a force.

Imaginary lines drawn so that their direction shows the direction of the electric field (arrows show the way a positive charge would move) and their spacing indicates relative field strength.

A device that converts mechanical energy into electrical energy by electromagnetic induction.

Electrical power is the rate at which electrical energy is transferred.

A magnet produced by an electric current, typically using a coil of wire; its strength can be controlled by changing the current.

The production of a voltage in a conductor when it experiences a changing magnetic field (or when it moves through a magnetic field).

The continuous range of all electromagnetic wavelengths and frequencies, divided into regions such as radio, microwaves, infrared, visible, ultraviolet, X‑rays and gamma rays.

A transverse wave made of oscillating electric and magnetic fields, perpendicular to each other and to the direction of travel.

A fundamental interaction in which electric charges and electric currents produce electric and magnetic fields, and changing fields can produce each other.

A fundamental particle with a **negative** electric charge of $-1.6\times 10^{-19}\,\text{C}$ and a very small mass of $9.1\times 10^{-31}\,\text{kg}$.

A fundamental particle with a negative electric charge of $-1.6\times 10^{-19}\,\text{C}$ and a very small mass of $9.1\times 10^{-31}\,\text{kg}$.

A force of attraction or repulsion between electric charges.

A process where a nearby charged object causes charges within a conductor to separate, producing regions of positive and negative charge without direct contact.

A closed, oval-shaped curve. In astronomy, an ellipse can describe a planet’s orbit with the Sun located at one focus rather than at the geometric center.

A source from which energy can be obtained for human use (for example, coal, sunlight, moving water, uranium).

Movement of energy from one object or system to another.

An energy transfer chain shows the sequence of energy stores and transfers in a process.

Change of energy from one form to another within a system or across interacting systems.

In a geocentric model, a small circular motion of a planet whose center itself moves on a larger circle around Earth, used to reproduce observed planetary motions.

The undisturbed position of the medium when no wave is passing (often shown as a dashed line).

Evaporation is a phase change in which a liquid turns into a gas at temperatures below its boiling point.

An imaginary boundary around a black hole beyond which nothing can escape to the outside universe.

Observations and measurements that support, contradict, or refine a hypothesis or theory.

An exoplanet is a planet that orbits a star outside the Solar System.

An experiment is a controlled way to collect measurements so you can decide whether a claim is supported.

A region of space where an object experiences a force because of the presence of another object (for example, a magnet or an electric charge).

Fleming’s left-hand rule is a method used to predict the direction of force on a current-carrying conductor in a magnetic field.

The emission of visible light by a substance after it absorbs higher-energy radiation such as ultraviolet.

A force is a mechanical interaction between two objects or bodies.

Fossil fuels are ancient energy sources formed over millions of years from the remains of plants and animals exposed to heat and pressure beneath Earth's surface

Motion in which gravity is the only significant force acting on an object.

A free-body diagram (FBD) is a simplified drawing that shows an object as a dot or box, with arrows for all external forces acting on it.

A diagram that represents an object as a point or simple shape with arrows showing all external forces acting on it.

Freefall occurs when gravity is the only force acting on an object.

Frequency is the number of complete waves passing a point each second.

Frequency refers to how often an individual engages in physical activity within a given period (e.g., per week).

The number of complete wave cycles that pass a point each second, measured in hertz (Hz).

Friction is a force that opposes motion between surfaces in contact.

A galaxy is a vast system of stars and matter held together by gravity.

A large collection of hundreds of billions of stars held together by gravity.

A model of the solar system in which Earth is at the center and the Sun, Moon, planets, and stars move around Earth.

The gravitational force per unit mass at a point in a gravitational field and is measured in $\text{N kg}^{-1}$.

The attractive force between any two objects that have mass.

Gravitational potential energy is the energy stored due to the position of an object in a gravitational field.

Gravity is the interaction that makes objects fall, gives us a sense of "up" and "down," and keeps moons, planets, and galaxies in orbit.

A greenhouse gas is a gas that contributes to the greenhouse effect by absorbing infrared radiation

Grounding (earthing) is the process of transferring excess charge safely to the Earth.

The half-life of a radioactive substance is the time taken for half of the unstable nuclei in a sample to decay.

Heat is energy transferred between objects due to a difference in temperature.

The movement of thermal energy from one object or region to another due to a temperature difference.

A model of the solar system in which the Sun is central and the planets (including Earth) orbit the Sun.

The relationship $v = H_0 d$ stating that the recession speed $v$ of a galaxy is proportional to its distance $d$ from the observer.

Hubble’s law states that the speed at which a galaxy moves away from us is proportional to its distance from us.

A testable prediction or proposed explanation that can be checked using observations or experiments.

The variable the experimenter deliberately changes to see its effect.

A way of reasoning where general principles are drawn from specific observations.

Inertia is the tendency of an object to resist changes in its motion.

Instantaneous velocity is the velocity of an object at a particular instant in time.

A material in which electrons do not move easily, so transferred charge tends to remain localized.

Interference is the combination of two or more waves when they overlap in the same region of space.

An ion is a charged atom formed by the gain or loss of electrons.

Radiation that can remove electrons from atoms or molecules, creating ions.

The process of forming ions by removing electrons from atoms or molecules (or adding electrons), often making a gas more electrically conductive.

Radiation that can remove electrons from atoms or molecules, creating ions.

Ionizing radiation is radiation with enough energy to remove electrons from atoms.

A region of Earth’s upper atmosphere containing charged particles that can reflect some radio waves, extending communication range.

At any junction in a circuit, the total current flowing into the junction equals the total current flowing out.

Kinetic energy is the energy an object possesses due to its motion.

A model of matter (especially gases) in which particles are in constant random motion and macroscopic properties like temperature and pressure arise from their collisions.

For reflection from a surface, the angle of incidence equals the angle of reflection: $i=r$ (angles measured to the normal).

Lift is the upward force produced by wings moving through air.

Lightning is a large-scale electrostatic discharge caused by strong electric fields.

A load is a component that transfers electrical energy into another form.

A wave in which the oscillations of the medium are parallel to the direction the wave travels.

A lunar eclipse occurs when the Earth is between the Sun and the Moon.

A tiny region inside a magnetic material where many atomic magnets (mainly due to electron behavior) are aligned in the same direction, so the region acts like a small magnet.

A region of space around a magnet (or other source) where magnetic forces act on magnetic materials or moving charges.

A line drawn so that its direction at any point shows the direction a compass needle would point; closer spacing of lines indicates a stronger magnetic field.

A force of attraction or repulsion between magnetic poles or between magnets and magnetic materials.

Describes a material that can be permanently deformed under compression (e.g., hammered or rolled) without breaking.

The amount of material in a body or object.

A value that combines a number and a unit to describe the size of a quantity (for example, 2.4 m, 15 g, 8 s).

The medium is the material through which a wave travels.

The material a wave travels through (for example, air for sound, water for surface waves, or a string for a wave on a rope).

A simplified representation of a system used to explain observations and make predictions; models are tested and refined as new evidence appears.

A mutation is a random change in DNA that introduces new genetic variants (alleles).

The vector sum of all forces acting on an object.

A particle in the nucleus with **no net charge** and a mass about $1.67\times 10^{-27}\,\text{kg}$.

The SI unit of force. $1\,\text{N} = 1\,\text{kg}\,\text{m}\,\text{s}^{-2}$.

Newton's first law states, "An object remains at rest or continues to move at constant velocity unless acted on by an external resultant force."

Newton’s Second Law of Motion states that the resultant force on an object is equal to the mass of the object multiplied by its acceleration.

When object A exerts a force on object B, object B exerts an equal-magnitude force on object A in the opposite direction.

Newton’s Third Law of Motion states that when one object exerts a force on another, the second object exerts an equal force in the opposite direction on the first.

A pair of forces of the same type and magnitude acting on two different objects, in opposite directions, arising from a single interaction.

A pair of forces from a single interaction: equal in magnitude, opposite in direction, same type, acting on two different objects.

An energy resource that will run out on a human timescale (roughly within 500 to 1,000 years) because it is not replaced fast enough.

An energy resource that will run out on a relatively short human timescale (roughly within 500–1000 years) because it is used much faster than it is naturally replaced.

An imaginary line drawn at 90° to a surface at the point where a wave (or ray) meets that surface.

A contact force exerted by a surface on an object, acting perpendicular to the surface.

A contact force exerted by a surface on an object, acting perpendicular to the surface.

Nuclear fission is the splitting of a heavy atomic nucleus into smaller nuclei, releasing energy and neutrons.

Nuclear fission is the splitting of atomic nuclei to release energy.

Energy stored in the nucleus of an atom due to short-range nuclear forces.

Nuclear waste is unwanted radioactive material produced by nuclear processes.

An orbit is a circular or elliptical path followed by an object as it moves around another object in space.

An orbit is a curved path followed by an object moving under the influence of gravity.

A parallel circuit is a circuit in which components are connected on separate branches.

A model that explains the behavior of materials by treating them as made of tiny particles (atoms or molecules) that are in constant motion and exert forces on each other.

A process in which other specialists evaluate scientific work before publication, checking methods, reasoning, and originality.

The time for one complete cycle of oscillation. It is related to frequency by $T=\frac{1}{f}$.

A phase diagram shows which state of matter exists under different temperature and pressure conditions.

A physical quantity is a measurable property that is described using a numerical value and a unit.

An object that orbits the Sun, is massive enough to be nearly round due to its own gravity, has cleared the neighborhood around its orbit, and is not massive enough to sustain nuclear fusion.

The liquid portion of the blood

The plum pudding model describes the atom as a positively charged sphere with negatively charged electrons spread throughout it.

The energy transferred per unit charge between two points in a circuit: $V=\dfrac{E}{Q}$.

Power is the rate at which energy is transferred or work is done.

The rate of energy transfer in a circuit: $P=\dfrac{E}{t}$.

How close repeated measurements are to each other (how consistent they are).

Pressure is force exerted per unit area on a surface.

A particle in the nucleus with **positive** electric charge $+1.6\times 10^{-19}\,\text{C}$ and a mass about $1.67\times 10^{-27}\,\text{kg}$.

Transfer of heat through infrared radiation, where the body radiates heat into the surroundings or absorbs heat from warmer objects or the sun.

Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation.

The process in which an unstable atomic nucleus spontaneously changes (decays), emitting particles and/or electromagnetic radiation.

A rarefaction is a region in a longitudinal wave where the medium's particles are spread apart, creating a low-pressure region.

Red shift is the increase in wavelength of light from an object moving away from the observer.

Reflection occurs when a wave strikes a surface and bounces back into the original medium.

Refraction is the bending of a wave as it passes from one medium to another, caused by a change in the wave’s speed.

The refractive index of a medium is the ratio of the wave speed in vacuum (or air) to the wave speed in the medium.

Reliability is the extent to which repeated measurements give similar results.

An energy resource that is naturally replenished on a short timescale compared with its rate of use, so it can be used sustainably if managed properly.

An energy resource that is replenished naturally at a rate comparable to human use (for example, sunlight, wind, flowing water, sustainably replanted biomass).

Resistance is a measure of how much a material opposes the flow of electric charge.

Resolution is the smallest change in a measurement that an instrument can detect.

The single force that has the same effect as all the forces acting together on an object (the **vector sum** of forces).

The resultant force is the single force that has the same effect as all the forces acting together.

The single force that has the same effect as all the forces acting together; it is the vector sum of all forces.

The apparent temporary reversal of a planet’s motion across the sky relative to the background stars.

If you point the thumb of your right hand in the direction of conventional current, your curled fingers show the direction of the magnetic field lines around the wire.

A natural object that orbits a larger body due to gravity, such as the Moon orbiting Earth.

A representation of a system or process used to explain observations and make predictions, often with known limitations.

A series circuit is a circuit in which all components are connected in a single loop.

SI units are internationally agreed standard units used for scientific measurement.

The Sun and all objects that orbit it or are otherwise gravitationally bound to it, including planets, moons, dwarf planets, asteroids, comets, and dust.

A long coil of wire; when current flows through it, it produces a magnetic field similar to that of a bar magnet, with a strong field inside the coil.

Sound is a type of wave, a traveling disturbance that transfers energy from one place to another.

A longitudinal mechanical wave in which particles of a medium oscillate back and forth parallel to the direction the wave travels, creating regions of compression and rarefaction.

Specific heat capacity is the energy required to raise the temperature of 1 kg of a substance by 1 °C (or 1 K).

Reflection from a smooth surface in which parallel incident rays remain parallel after reflection, producing a clear image.

A physical form of a substance (such as solid, liquid, gas, or plasma) determined by how its particles are arranged and how strongly they interact.

Static electricity is the accumulation of electric charge on an object, usually caused by the transfer of charge between materials.

The build-up of electric charge on an object’s surface that remains in place (rather than flowing as an electric current) until it discharges.

A transformer that decreases voltage from the primary coil to the secondary coil (secondary has fewer turns).

A transformer that increases voltage from the primary coil to the secondary coil (secondary has more turns).

A change of state in which a substance transitions directly from solid to gas without passing through the liquid state.

Sustainability is meeting present needs without harming future generations’ ability to meet theirs.

Temperature is a measure of how hot an object is, linked to the average kinetic energy of its particles.

Tension is a pulling force in a stretched object.

A small (imaginary) positive charge used to define the direction and strength of an electric field without significantly disturbing it.

The branch of physics that studies temperature, heat energy, and how energy transfers due to temperature differences, often using particle (kinetic) models of matter.

Electromagnetic radiation emitted by matter due to its temperature, transferring energy without needing contact or a material medium.

The time taken for one full oscillation (cycle) of the medium at a point.

Describes a solid that is difficult to break and resists fracture when deformed.

A device that converts energy from one form to another, for example electrical energy to ultrasound and back again.

A transformer is a device that changes the voltage of an alternating current (AC) using the principles of electromagnetic induction.

A wave in which the oscillations of the medium are perpendicular (at right angles) to the direction the wave travels.

Charging by friction or contact, where electrons are transferred between two materials, leaving one negatively charged and the other positively charged.

A ranking of materials by how strongly they tend to lose electrons (becoming positive) or gain electrons (becoming negative) when in contact and then separated.

A turbine is a device that rotates when a moving fluid such as steam, water, or air flows over it.

Sound with frequency above the upper limit of human hearing (about $20\ \text{kHz}$).

An estimate of the range within which the true value of a measurement is expected to lie.

An electric field with constant magnitude and direction throughout a region, represented by straight, parallel, equally spaced field lines.

A gravitational field in which the field strength is constant and the field lines are parallel, meaning the force on a given mass is the same everywhere in the region.

A magnetic field that has the same strength and direction at every point in a region (represented by straight, parallel, equally spaced field lines).

Upthrust is the upward force exerted by a fluid on an object immersed in it.

Upthrust is the upward force exerted by a fluid on an object.

The upward force a fluid exerts on an object that is submerged or floating.

A region with very low gas particle density and pressure, but not necessarily zero particles.

A voltmeter is a device used to measure voltage.

A travelling disturbance/oscillation that transfers energy (and information) through space or a medium without a net transfer of matter.

The relationship $v=f\lambda$ that links wave speed $v$, frequency $f$, and wavelength $\lambda$.

The rate at which a wave pattern (a crest, compression, or other point of constant phase) moves through a medium.

The distance between two points on a wave that are in the same phase, such as from one compression to the next compression.

The distance along a wave for one complete cycle, for example from one compression to the next compression.

The gravitational force acting on an object due to a gravitational field.