Chapter 14 – Energy Lecture Notes

Vocabulary terms and definitions related to thermal energy, heat transfer methods, cooling systems, and infrared radiation based on Chapter 14.

Thermal Energy

Also called heat energy, it is the total kinetic energy (movement energy) of atoms and molecules inside a substance.

Temperature

A measurement showing how hot or cold an object is by measuring the average kinetic energy of particles.

Joulemeter

A device used to measure the amount of electrical energy used when heating a substance.

Law of Conservation of Energy

Scientific law stating that energy cannot be created or destroyed, only changed from one form to another.

Exothermic reactions

Chemical reactions that release energy as heat or light.

Endothermic reactions

Chemical reactions that absorb energy from their surroundings.

Heat Transfer

The movement of heat energy from hotter areas to cooler areas.

Conduction

The transfer of heat through direct contact of particles, happening mainly in solids.

Conductors

Materials, such as metals, that allow heat to pass through them easily.

Insulators

Materials, such as wool or plastic, that do not allow heat to pass easily.

Sea of electrons

The structure in metals where outer electrons move freely, allowing them to carry heat and electricity quickly.

Convection

Heat transfer by the movement of liquid or gas particles, occurring only in fluids and never in a vacuum.

Convection currents

Patterns created when warm liquid rises because it is less dense and cooler liquid moves down to replace it.

Radiation

Heat transfer through waves that does not need particles or a medium and can travel through a vacuum.

Evaporation

The process where high-energy liquid particles escape into the air as gas, causing a cooling effect.

Refrigerant

A liquid used inside a refrigerator to remove heat by changing between gas and liquid states.

Compressor

The refrigerator component that receives gas and squeezes it, creating hot, high-pressure gas.

Condenser coils

Parts at the back of a fridge where heat leaves the refrigerant gas and goes into the air, changing it into a liquid.

Expansion chamber

The part of the refrigerator system where liquid refrigerant evaporates into gas to absorb heat.

Thermostat

A device that controls the refrigerator temperature by switching it off when it is cold enough.

Thermal Imaging

The process of using infrared radiation detected by special cameras to create pictures from heat converted into electrical signals.

William Herschel

The scientist who discovered infrared radiation in 1800 using a prism to find invisible heat just beyond red light.

Macedonio Melloni

A scientist who developed a device that could detect heat from $10\,m$ away.

Samuel Pierpont Langley

A scientist who created a device that could detect heat from $400\,m$ away.

Greenhouse Effect

A warming effect caused when sunlight entering through glass is absorbed by the ground and transformed into trapped infrared radiation.