Which type of radiation can be stopped by clothing or aluminum foil?

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

Answer: (D)

The correct answer is based on the characteristics of the types of radiation listed. Beta particles consist of high-energy, high-speed electrons or positrons that are emitted from certain radioactive materials during the decay process. They have a relatively low mass and charge compared to other types of radiation, allowing them to be effectively stopped by materials like clothing or aluminum foil. This makes beta radiation less penetrating than alpha particles in terms of shielding materials.

In contrast, alpha particles, which are heavy and positively charged, can be stopped by a sheet of paper or even the outer layer of skin, but they are not the right answer in this case since the option specifically refers to the ability of clothing or aluminum foil to stop them. Gamma rays are highly penetrating electromagnetic radiation that typically require dense materials like lead or several centimeters of concrete for effective shielding, which makes them unsuitable for stopping with clothing or foil. Neutrons, being neutral particles, also require substantial shielding, like water or concrete, for effective attenuation, further reinforcing why they do not fit the question's requirement. Thus, beta particles are the correct choice when considering the capabilities of common, lightweight materials in stopping radiation.