Heat
Atoms and molecules are always vibrating; their heat energy flows from hotter substances or regions to colder ones.
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Heat Energy and Molecular Motion
Atoms and molecules are always vibrating; their heat energy flows from hotter substances or regions to colder ones.
Open article →Thermal Expansion
Heating makes particles vibrate and separate, causing expansion in solids, liquids and gases, with the greatest expansion in gases.
Open article →Temperature Rise on Heating
When molecules receive heat, their kinetic energy increases and the substance's temperature rises.
Open article →Heat and Changes of State
Heating weakens attraction so ice melts and water vaporises; removing heat reverses changes among solid, liquid and gas.
Open article →Conduction in Solids
Conduction transfers heat through a solid from higher to lower temperature without actual movement of its atoms or molecules.
Open article →Convection in Liquids and Gases
In convection, heated fluid rises and cooler fluid descends, transferring heat by actual molecular movement.
Open article →Heat Transfer by Radiation
Radiation transfers heat as electromagnetic waves through empty space, allowing solar heat to reach Earth.
Open article →Temperature Scales, Namesakes and Heat Units
Learn who Celsius, Fahrenheit and Kelvin are named after, their fixed points and conversions, and how heat is measured in joules and calories.
Open article →Calorimetry and the Calorimeter
Calorimetry measures heat involved in a process; a calorimeter uses a conducting metal vessel and an insulating jacket to limit heat loss.
Open article →Heat Capacity: Formula and Unit
Heat capacity C' is the heat energy Q needed for temperature rise ΔT: C' = Q/ΔT, measured in J K⁻¹ in SI.
Open article →Specific Heat Capacity: Formula and Unit
Specific heat capacity C is heat Q per mass m and temperature rise ΔT: C = Q/(mΔT), with SI unit J kg⁻¹ K⁻¹.
Open article →Thermostat: Temperature Sensing and Control
A thermostat maintains a preset temperature by turning an appliance or circuit on or off and may act as both sensor and controller.
Open article →Thermos Flask and Heat-Transfer Control
A thermos flask uses evacuated double walls, insulated supports and silvered surfaces to reduce conduction, convection and radiation.
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