Topic 2 Temperature and Heat

Heat

A form of energy that causes a rise in temperature when added or a fall in temperature when withdrawn, unit: joules (J)

Temperature

A measure of the hotness or coldness of any object

A thermometric property

A physical property that changes measurably and repeatedly with temperature change

Heat capacity (C)

The amount of heat energy needed to change the temperature of a substance by 1 kelvin, unit: JK⁻¹

Specific heat capacity (c)

The amount of heat energy needed to change 1kg of a substance by 1 kelvin, unit: Jkg⁻¹K⁻¹

Latent heat (L)

The amount of heat energy needed to change the state of a substance without a change in temperature, unit: J

Specific latent heat (l)

The amount of heat energy needed to change the state of 1kg of a substance without a change in temperature, unit: Jkg⁻¹

Specific latent heat of vaporisation

The amount of heat energy needed to change 1kg of a substance from liquid to gas without a change in temperature

Vapour change

The change from gas to liquid (specific latent heat of vaporisation emitted)

Specific latent heat of fusion

The amount of heat energy needed to change 1kg of the substance from solid to liquid without a change in temperature

Fusion change

The change from liquid to solid (specific latent heat of fusion emitted)

Conduction

The transfer of heat energy in a solid by passing on kinetic energy from molecule to molecule

Convection

The transfer of heat energy by the circulation of the heated parts of a liquid or gas

Radiation

The transfer of heat energy as electromagnetic (EM) waves without the need for a medium

Solar constant (Solar irradiance)

The amount of solar energy striking 1m² of the Earth's atmosphere every second, unit: Wm⁻²

U-value

The amount of heat energy that can be transmitted across 1m² of a material's surface every second, so long as there is a temperature difference of 1K on each side of the material, unit: Wm⁻²K⁻¹