Which radiation consists of particles with large mass and a positive charge, and is the least penetrating among common radiation forms?

Which radiation consists of particles with large mass and a positive charge, and is the least penetrating among common radiation forms?

• A. Beta Radiation
• B. Alpha Radiation
• C. Gamma Radiation
• D. Neutron Radiation

Answer: (B)

Alpha radiation is made of helium nuclei—two protons and two neutrons. That combination gives it relatively large mass and a +2 electric charge, which makes it interact with matter very strongly and lose energy quickly as it ionizes atoms along its short path. Because of this strong interaction, alpha particles travel only a short distance in air and can be blocked by a sheet of paper or just the outer layer of skin. That is why they are the least penetrating among the common forms of radiation. In contrast, beta particles (fast electrons) are lighter and negatively charged, so they penetrate more and are stopped by plastic or thin metal; gamma rays are massless photons with no charge and penetrate deeply, requiring dense shielding such as lead or concrete; neutrons, while uncharged, can also penetrate and require hydrogen-rich materials to slow and capture them.

Alpha radiation is made of helium nuclei—two protons and two neutrons. That combination gives it relatively large mass and a +2 electric charge, which makes it interact with matter very strongly and lose energy quickly as it ionizes atoms along its short path. Because of this strong interaction, alpha particles travel only a short distance in air and can be blocked by a sheet of paper or just the outer layer of skin. That is why they are the least penetrating among the common forms of radiation. In contrast, beta particles (fast electrons) are lighter and negatively charged, so they penetrate more and are stopped by plastic or thin metal; gamma rays are massless photons with no charge and penetrate deeply, requiring dense shielding such as lead or concrete; neutrons, while uncharged, can also penetrate and require hydrogen-rich materials to slow and capture them.