Physics: Thermal Energy

Heat

Energy that flows between objects due to a difference in temperature.

Thermal equilibrium

When two objects have the same temperature and cease to exchange heat.

Zeroth law of thermodynamics

If objects A and B are in thermal equilibrium with object C, then objects A and B are in thermal equilibrium with each other.

Thermal expansion

The increase in length or volume of a substance when it is heated.

Behavior of water between 0°C and 40°C

Water contracts when the temperature increases and expands when the temperature decreases within this temperature range.

Internal energy

The total energy of the particles in a substance, consisting of both kinetic and potential energy.

Heat capacity

The amount of heat energy required to raise the temperature of a body by 1 degree.

Specific heat capacity

The amount of heat energy required to raise the temperature of 1kg of a substance by 1 degree.

Latent heat

The heat absorbed or released during a change of state without a change in temperature.

Conduction

The transfer of heat energy through direct contact between particles.

Convection

The transfer of heat energy through the movement of particles in a fluid.

Radiation

The transfer of heat energy through electromagnetic waves.

Convection

The movement of air caused by differences in temperature, with warmer air being less dense and more buoyant than cooler air.

Natural convection

The cooling and heating of a mass of molecules that occurs without any external force, such as land and sea breezes or rising convection currents of warm air (thermals) used in hang gliding.

Forced convection

Convection that occurs when an outside object, such as a fan, causes a substance to undergo convection by heating it and blowing away the hot air.

Thermal radiation

Electromagnetic waves emitted by objects as a result of their temperature, which can transfer heat without the need for matter.

Black body

An object that absorbs all radiation that falls on it and reflects or transmits none, making it a good absorber and emitter of radiation.

Shiny surfaces

Surfaces that reflect most radiation and are poor absorbers and emitters of radiation.

Greenhouse effect

The process in which the Earth emits long-wavelength radiation that is trapped or absorbed by greenhouse gases, leading to an increase in atmospheric temperature.

Vacuum

A space devoid of matter that can block heat transfer by conduction, convection, and radiation, commonly used in vacuum flasks or thermos.

Solar water heater

A system that uses solar collectors to heat water stored in a tank, often used for industrial, agricultural, and daily life purposes.

Heat loss reduction in houses

Various methods to reduce heat transfer in houses, including installing double glazing, loft insulation, cavity wall insulation, draught excluders, and reflective aluminum foil behind radiators.

Factors affecting emission/absorption rates of infrared radiation

The color and texture of a surface, surface temperature, and surface area can affect the emission and absorption rates of infrared radiation.