Which type of radiation can be stopped by a sheet of paper?

Alpha particles are primarily helium nuclei and are relatively large and heavy compared to other forms of radiation. Due to their mass and double positive charge, alpha particles interact strongly with matter. When encountering materials, they quickly lose energy and can be completely stopped by even a single sheet of paper or the outer layer of human skin. This property makes alpha particles less penetrating than other types of radiation, such as beta particles, gamma rays, or X-rays, which require denser materials for shielding.

Understanding the penetration power of different radiation types is essential in radiation safety. Alpha particles are a common concern in scenarios involving radioactive substances, but their limited range means that with proper precautions, such as a simple barrier like paper, one can effectively protect against exposure.