Energy - Thermal Energy Transfer

Thermal energy always transfers from a region of higher temperature to a region of lower temperature until thermal equilibrium is reached.

Conduction: The process where thermal energy is passed through a substance by the vibration of atoms and the movement of free electrons. It is most effective in solids, especially metals, which have a high density of free electrons ($e^-$).

Convection: Thermal energy transfer in fluids (liquids and gases) caused by differences in density. When a fluid is heated, it expands, its density decreases ($ho = \frac{m}{V}$), and it rises, creating a convection current.

Radiation: The transfer of energy by infrared (IR) electromagnetic waves. Unlike conduction and convection, radiation does not require a medium and can travel through a vacuum. Surface properties affect this: dull, black surfaces are the best absorbers and emitters, while shiny, silver surfaces are the best reflectors.

Specific Heat Capacity ($c$): The amount of energy required to raise the temperature of $1\text{ kg}$ of a substance by $1\text{ }^\circ\text{C}$ (or $1\text{ K}$). It is measured in $\text{J kg}^{-1}\text{ }^\circ\text{C}^{-1}$.

Specific Latent Heat ($L$): The energy required to change the state of $1\text{ kg}$ of a substance without a change in temperature. $L_f$ is for fusion (melting/freezing) and $L_v$ is for vaporization (boiling/condensing).