Positronium is an atom composed of an electron and a positron (mass m = me, charge q = +...

Positronium is an atom composed of an electron and a positron (mass m = m_e, charge q = +e). Calculate the distance between the particles and the energy of the lowest energy state of positronium. (Hint: what is the reduced mass of the two particles? See Problem 53.)

Problem 53

The proton (mass M) and electron (mass m) in a hydrogen atom actually rotate about their common center of mass as shown in Figure 4.17. The distance r = r_e + r_M is still defined to be the electron-nucleus distance. Show that Equation (4.24) is only modified by substituting for m by