Section C - Thermal physics and kinetic theory: Key terms and concepts

A set of vocabulary-style flashcards covering the main concepts of heat transfer, conduction, convection, radiation, and related topics from the notes.

Heat transfer

The movement of thermal energy from a region of higher temperature to a region of lower temperature, occurring by conduction, convection, or radiation.

Conduction

Heat transfer through a solid or stationary medium by transfer of kinetic energy between colliding particles and free electrons; rate depends on material, thickness, and cross-sectional area.

Convection

Heat transfer by the bulk movement of fluids (liquids or gases) due to density differences; produces convection currents and cannot occur in solids.

Radiation

Heat transfer by electromagnetic waves that can occur in a vacuum; all objects emit and absorb radiant energy; no medium required.

Conductor

A material that easily transfers heat (e.g., many metals) often due to free electrons.

Insulator

A material that resists heat transfer (e.g., air, wool, fiberglass); often traps air to reduce conduction and convection.

Vacuum flask

A double‑walled container with a vacuum between walls and reflective inner surfaces to minimize heat loss by conduction, convection, and radiation.

Double glazing

Two parallel panes of glass with an air or gas-filled space between them to reduce heat transfer, especially by convection.

Black body

An ideal absorber and emitter of radiant energy; black surfaces absorb and emit radiant energy more efficiently than shiny surfaces.

Leslie’s cube

A hollow cube with surfaces of different finishes used to compare the emission of radiant energy from each surface.

Greenhouse effect

The warming of Earth's surface due to greenhouse gases (like CO2 and water vapour) trapping infrared radiation, allowing sunlight in but reducing heat escape.

Specific heat capacity

The amount of heat required to raise the temperature of 1 kg of a substance by 1°C; water has a high specific heat capacity (~5 times that of soil), so land heats and cools more quickly than water.

Sea breeze

Daytime wind where warm air over land rises and cooler air from the sea moves in, due to land heating faster than the sea.

Land breeze

Nighttime wind where cooler air from land moves toward the sea as air over the sea remains warmer and rises.

Solar cooker

A device with a curved polished reflector that concentrates sunlight onto a pot or dish to heat it.

Thermal conductivity

The property of a material that determines how readily heat is conducted; metals are generally good conductors, non‑metals poorer; depends on material, thickness, and cross-sectional area.

Wax test for thermal conductivity

An experimental method in which wax-coated nails attached to rods are heated; the nail that falls off first indicates a better conductor.

Infrared radiation

A portion of the electromagnetic spectrum emitted by hot bodies; humans emit mainly in the far infrared region; heat can be detected with infrared devices.

Absorption and emission of radiant energy

Radiant energy can be absorbed or reflected by surfaces; good absorbers (dark/rough surfaces) are also good emitters of radiation.

Thermopile

A detector used to measure radiant energy by converting infrared radiation into an electrical signal.

Reflection of radiant energy

Portions of radiant energy can be reflected by surfaces; polished surfaces tend to reflect more than rough/blackened ones.

Water as a poor conductor

Water is a poor conductor of heat compared with metals; conduction in water is relatively slow, as demonstrated by slow ice melting when a hot block is placed nearby.

Air as an insulator

Air resists heat transfer and serves as an effective insulator when trapped in materials like fiberglass, styrofoam, and wool; convection in air can still occur if not trapped.