Absorption and Emission of Radiation

All materials absorb and emit thermal radiation, which is a form of electromagnetic radiation.
The amount of radiation absorbed, reflected or transmitted by a surface depends on the type of surface and its colour.
Dark and matt surfaces are good absorbers and emitters of thermal radiation, whereas light and shiny surfaces are poor absorbers and good reflectors of thermal radiation.
The Earth’s surface absorbs radiation from the Sun, which causes it to heat up. This absorbed heat is later emitted as radiated heat back into the environment.
Greenhouse effect is related to the absorption and emission of radiation. Certain gases in the Earth’s atmosphere, like carbon dioxide and methane, trap some of the emitted radiation from the Earth’s surface, preventing it from escaping into space and thus causing the planet to warm up.
The amount of radiation absorbed and emitted by an object is directly related to its temperature. The hotter an object is, the more thermal radiation it emits.
The Stefan-Boltzmann Law describes this relationship between an object’s temperature and the amount of radiation it emits.
Different substances absorb and emit radiation at different rates. For instance, metals generally absorb and emit radiation faster than non-metals.
The Earth’s climate is largely regulated by the balance between the amount of solar radiation that is absorbed by the Earth’s surface and the amount of thermal radiation that is emitted back into space.
Infrared radiation is absorbed by the skin, resulting in a sensation of heat. This is the basis of infrared heaters and heat lamps commonly used for heating.
Beyond ISO 14001, there’s a push for businesses to reduce their emission of thermal radiation (also known as their carbon footprint) to minimise their impact on global warming.
Another practical application of the concept of absorption and emission of radiation is in solar panels. These devices absorb radiation from the Sun and convert it into electrical energy.
In astronomy, studying the radiation emitted by stars and other celestial bodies can provide insight about their temperature, composition and other physical properties.
In healthcare, thermal imaging cameras can be used to detect variations in thermal radiation from different parts of the body, which can be an indication of conditions such as inflammation, infection or tumour growth.