X-rays vs gamma rays: which penetrates farther?

• A. X-rays
• B. Gamma rays
• C. Alpha particles
• D. Beta particles

Answer: (B)

Gamma rays generally penetrate farther. They are high-energy, uncharged electromagnetic waves produced by atomic nuclei, so they interact with matter less readily than X-rays of typical energies. That means they pass through thicker materials before losing energy, whereas alpha particles are stopped almost instantly by a sheet of paper and beta particles by a few millimeters of tissue or metal. In the continuum of radiations, gamma rays tend to have greater penetrating power than X-rays, making shielding thicker and more substantial for gamma exposure.