Which type of radiation has the highest penetrating power?

Gamma radiation is known for having the highest penetrating power among the types of radiation listed. This is because gamma rays are high-energy electromagnetic radiation, which allows them to travel through materials with greater ease compared to alpha and beta radiation.

Alpha radiation consists of heavy, positively charged particles and has low penetrating power; it can be stopped by a sheet of paper or even the outer layer of human skin. Beta radiation, on the other hand, consists of lighter charged particles (electrons) and has a greater ability to penetrate materials than alpha particles but still can be stopped by a few millimeters of plastic or glass.

In contrast, gamma rays can pass through most substances, including human tissue, concrete, and lead, though dense materials can reduce their intensity. X-ray radiation also has significant penetrating ability, but gamma rays possess higher energy and penetrative capacity due to their source originating from nuclear reactions rather than electron transitions, making gamma radiation the most penetrating of the options provided.