Which type of radiation has the greatest penetrating power?

Gamma rays exhibit the greatest penetrating power among the types of radiation listed due to their nature as high-energy electromagnetic waves. Unlike alpha particles, which can be stopped by a sheet of paper or skin, and beta particles, which can penetrate a few millimeters into materials but are generally halted by plastic or glass, gamma rays are highly penetrating due to their lack of mass and charge. They can pass through most materials, including human tissue and thick barriers like lead or concrete, although significantly dense materials are required to attenuate their intensity effectively.

In addition, neutrons, while also capable of penetrating materials, do so through different mechanisms and generally require specific conditions (such as high atomic number materials) to be effective. Gamma rays, with their high energy and electromagnetic nature, remain the most penetrating form of radiation, allowing them to travel long distances in a variety of media without being easily absorbed.