One form of nuclear radiation, beta decay, occurs when a neutron changes into a proton, an electron, and a neutral particle called a neutrino: n → p⁺ + e^- + ν where ν is the symbol for a neutrino. When this change happens to a neutron within the nucleus of an atom, the proton remains behind in the nucleus while the electron and neutrino are ejected from the nucleus. The ejected electron is called a beta particle. One nucleus that exhibits beta decay is the isotope of hydrogen ³H, called tritium, whose nucleus consists of one proton (making it hydrogen) and two neutrons (giving tritium an atomic mass m = 3 u). Tritium is radioactive, and it decays to helium: ³H → ³He + e^- + ν.
a. Is charge conserved in the beta decay process? Explain.
b. Why is the final product a helium atom? Explain.
c. The nuclei of both 3H and 3He have radii of 1.5 × 10^-15 m.
With what minimum speed must the electron be ejected if it is to escape from the nucleus and not fall back?