Thermal radiation is the process through which energy is emitted from a heated surface in all directions in the form of electromagnetic radiation. The emitted radiation travels directly to its point of absorption at the speed of light.
No intervening medium or mass is required for thermal radiation to take place. All objects take in and give out thermal radiation, which is sometimes referred to as infrared radiation. The radiation emitted by an object is typically as a result of the thermal agitation of its composite molecules. Stefan-Boltzmann law states that the heat energy emitted by heated surface per unit area per second is directly proportional to the fourth power of the surface's absolute temperature.