Final answer:
All the listed sources contribute to background radiation, including cosmic rays from space, residuals from atomic bomb testing, and emissions from nuclear power plants. The radiation we are exposed to daily comes from a mix of natural and artificial sources, with a significant portion being natural.
Step-by-step explanation:
Sources of background radiation include a) Cosmic rays from space. b) Atomic bomb testing. c) Nuclear power plants. d) All of the above. The correct answer is d) All of the above, as background radiation, encompasses not only natural sources but also certain human-made sources.
We encounter background radiation daily through various means. Cosmic rays from space are a significant natural source. They interact with gases in our atmosphere, leading to the creation of radioactive isotopes like carbon-14. On the ground, we have radioactive elements in the soil, such as thorium and uranium, and their decay products, including radon gas. Human-made sources include residuals from atomic bomb testing and emissions (although highly controlled and regulated) from nuclear power plants. The average annual radiation dose per person in the U.S. is 6.2 millisieverts (620 millirems), largely sourced from these natural and artificial origins.
It is essential to understand that while we can minimize exposure, it is impossible to eliminate it entirely. Precautions can be taken such as using shields, maintaining a distance from the source, and reducing exposure time, particularly concerning artificial radiation sources.