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

Alpha particles are relatively large and heavy subatomic particles that consist of two protons and two neutrons, making them positively charged. Due to their mass and charge, alpha particles interact strongly with matter. When encountering materials, they tend to lose energy quickly. A sheet of paper is sufficient to stop alpha particles because the paper's atoms can easily absorb the energy from these particles, preventing them from penetrating any further.

In contrast, beta particles, which are electrons or positrons, have greater penetration power compared to alpha particles and can pass through paper but are generally stopped by materials like plastic or a few millimeters of aluminum. X-rays and gamma rays, which are forms of electromagnetic radiation, have even more penetrating power than beta particles and require denser materials like lead or concrete for effective shielding. This understanding helps in recognizing the different properties of radiation types and their interactions with various materials.