Physics – 2.3.3 Radiation | e-Consult

Thermal radiation is a form of electromagnetic radiation. Electromagnetic waves do not require a medium to travel; they can propagate through a vacuum. This is because electromagnetic waves are self-propagating; a change in the electric field creates a changing magnetic field, which in turn creates a changing electric field, and so on. The spectrum of thermal radiation emitted by an object depends on its temperature. As temperature increases, the peak wavelength of the emitted radiation decreases (Wien's displacement law). At lower temperatures, the emitted radiation is predominantly infrared. As the temperature increases, the emitted radiation shifts towards the visible spectrum (red, then orange, then yellow, etc.) and eventually towards ultraviolet radiation at very high temperatures. The intensity of the thermal radiation also increases with temperature, following the Stefan-Boltzmann law.