Radiation Safety Practice Exam

Which type of radiation penetrates more effectively than alpha particles but generates fewer ions?

1. Alpha particles

2. Beta particles

3. Gamma rays

4. X-rays

The correct answer is: Beta particles

Beta particles are indeed more penetrating than alpha particles and generate fewer ions as they pass through matter. Alpha particles are relatively heavy and positively charged; therefore, they interact strongly with matter, leading to a high ionization density but low penetration. They can be stopped by a sheet of paper or even the outer layer of human skin. In contrast, beta particles, which are electrons or positrons, are lighter and carry a negative or positive charge. They can penetrate materials more effectively than alpha particles due to their lower mass and charge, allowing them to travel further into matter before being absorbed or scattered. However, their ionization capability is lower than that of alpha particles because they interact less strongly with matter. Gamma rays and X-rays are forms of electromagnetic radiation and also have significant penetrating power. However, they generate even fewer ions compared to beta particles due to their neutral charge and ability to pass through materials without interaction unless the energy is sufficiently high to result in Compton scattering or photoelectric absorption. Thus, when considering effective penetration and ionization, beta particles are the best choice among the given options.