Which term refers to the natural radiation that comes from cosmic rays, the earth, and radioactive materials?

The term that refers to the natural radiation originating from cosmic rays, the Earth, and radioactive materials is background radiation. This type of radiation is consistently present in the environment and encompasses various sources, including cosmic radiation from outer space and radiation emitted from naturally occurring radioactive isotopes found in soil and rocks.

Background radiation is significant because it contributes to the overall exposure of living organisms to radiation. It is a normal and unavoidable part of life on Earth, contrasting with artificial sources of radiation such as those from medical treatments or nuclear power plants, which are typically controlled and monitored.

In the context of this question, while ionizing radiation does encompass background radiation, it is a broader term that includes any radiation capable of ionizing atoms. Thermal radiation refers to radiation emitted by matter as a result of its temperature and does not pertain specifically to the natural environmental radiation described. Electromagnetic radiation is a general term that encompasses a range of radiation types but does not specifically denote natural or background sources. Therefore, background radiation captures the concept of radiation that is naturally occurring in our environment.