Radiation Safety Practice Exam

Which statement is true about beta particles?

1. They are heavier than protons.

2. They have the same mass as an electron.

3. They carry a positive charge.

4. They can be stopped by a sheet of paper.

The correct answer is: They have the same mass as an electron.

Beta particles are indeed closely related to electrons, as they are essentially high-energy, high-speed electrons or positrons (the antiparticle of electrons) emitted during certain types of radioactive decay processes. Specifically, when beta decay occurs in a radioactive atom, a neutron is transformed into a proton, resulting in the release of a beta particle, which is an electron in this case. Thus, the correct statement is that beta particles have the same mass as an electron. In terms of mass, both beta particles and electrons have an approximate mass of 0.511 MeV/c² (million electron volts per speed of light squared), making their masses equivalent. The misconception that beta particles could be heavier than protons overlooks their actual composition and properties; they are much lighter than protons and neutrons. Additionally, while it’s true that beta particles can interact with materials, they are not stopped by a sheet of paper; a sheet of aluminum or plastic is needed to effectively absorb them. Lastly, beta particles are not positively charged; they can be negatively charged electrons or positively charged positrons, so this statement is also inaccurate.