What is the radius of an alpha particle?

Video Transcript

This is College Physics Answers with Shaun Dychko. The radius of a nuclide is given by this equation— r naught times the mass number to the power of one-third— this is equation [31.7]. r naught is 1.2 fermis, or femtometers, and for a α-particle, the mass number is 4 because there are 4 nucleons in the helium nuclide and raise that to the power of one-third and you get 1.9 femtometers.