What type of radiation can be effectively stopped by paper or skin?

• A. Beta particles
• B. Alpha particles
• C. Gamma rays
• D. Neutron particles

Answer: (B)

Alpha particles are a type of radiation that consist of two protons and two neutrons, making them relatively heavy compared to other forms of radiation. Because of their larger mass and charge, alpha particles have a very limited range and low penetration power. They can be effectively stopped by just a few centimeters of air or by materials such as paper or even the outer layer of human skin. This characteristic makes alpha particles relatively safe when outside the body, although they can be harmful if ingested or inhaled.

In contrast, other types of radiation, like gamma rays and neutron particles, require much denser materials such as lead or concrete for effective shielding, and beta particles can penetrate further than alpha particles, necessitating thicker or more dense barriers. Understanding the differences in penetration abilities helps in assessing the appropriate protective measures when dealing with various types of radiation in hazardous materials situations.