IB Physics B.1.3 Mechanisms of Thermal Energy Transfer Key Definitions

Apparent brightness is a measure of how bright an object appears to an observer. It depends on both the intrinsic luminosity $L$ of the object and its distance $d$ from the observer.

A black body is an idealized object that absorbs all radiation falling on it and emits radiation based on its temperature.

Conduction is the transfer of thermal energy through a material without the movement of the material itself.

Convection is the transfer of thermal energy through the bulk movement of fluid particles, driven by differences in density caused by temperature differences.

Radiation is the transfer of thermal energy away from a body by electromagnetic waves (such as infrared, visible light or ultraviolet), without the need for a material medium.