Thermal Equilibrium

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Heat Noun

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[heet]

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Heat

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Energy that is in transit, flowing from a region of higher temperature to a region of lower temperature.

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Example: This diagram shows that heat is the transfer of thermal energy, which always flows from a hotter object to a colder object.

Front

Temperature Noun

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[tem-per-uh-cher]

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Temperature

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A physical quantity that determines the direction of heat flow and indicates if systems are in thermal equilibrium.

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Example: This image shows a thermometer, a tool used to measure temperature, which is the degree of hotness or coldness of an object.

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Conduction Noun

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[kon-duk-shun]

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Conduction

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The mechanism of heat transfer through direct contact and collision between particles of a substance without bulk movement.

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Example: Heat from the stove travels through the solid metal pan to the handle, showing how thermal energy is transferred by direct contact.

Front

Convection Noun

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[kon-vek-shun]

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Convection

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The mechanism of heat transfer through the bulk movement of fluids, such as liquids or gases.

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Example: Heat from the flame warms the water at the bottom, causing it to become less dense and rise. Cooler, denser water from the top sinks to take its place, creating a circular flow called a convection current.

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Radiation Noun

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[ray-dee-ay-shun]

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Radiation

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The mechanism of heat transfer through electromagnetic waves, which can travel through a vacuum without a medium.

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Example: The Sun transfers heat energy to the Earth through space using electromagnetic waves, a process called radiation.

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Conductor Noun

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[kon-duk-ter]

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Conductor

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A material that allows thermal energy to pass through it easily with minimal resistance to heat flow.

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Example: This image shows a metal rod, a conductor, being heated at one end, causing thermal energy to travel along the rod to the colder end.

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Insulator Noun

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[in-suh-lay-ter]

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Insulator

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A material that hinders or significantly slows down the transfer of heat due to its low thermal conductivity.

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Example: This diagram shows how an insulator works by using a foil facing to reflect heat and discontinuous fibers to trap air, slowing down heat transfer.

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Thermal Contact Noun

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[thur-muhl kon-takt]

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Thermal Contact

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A condition in which two systems are able to exchange heat energy with each other across a boundary.

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Example: When objects are in thermal contact, faster particles from the hot side collide with and transfer energy to slower particles on the cold side.

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Diathermic Wall Noun

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[dy-uh-thur-mik wawl]

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Diathermic Wall

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A boundary that allows the transfer of heat between two systems but prevents the transfer of matter.

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Example: This diagram shows a diathermic wall separating two areas. The arrows labeled 'Q' represent heat energy passing through the wall, which is what allows two systems to eventually reach the same temperature (thermal equilibrium).

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Adiabatic Wall Noun

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[ay-dee-uh-bat-ik wawl]

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Adiabatic Wall

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A perfectly insulating boundary that completely prevents any transfer of heat between a system and its surroundings.

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Example: This diagram shows a container separated by a thick wall. A heater on one side increases the temperature, but the adiabatic wall prevents heat from passing through to the other side.