For ordinary hydrogen, the reduced mass of the electron and proton is mt = 0.99946m, where m is the electron mass (see Section 38.5). For each of the following cases, find the numerical coefficient of -l/n2 in Eq. (41.3) and the energy of the photon emitted in a transition from the n = 2levelto the n = 1 level:
(a) A hydrogen atom in which the nucleus is taken to be infinitely massive, so mr = m;
(b) Positronium (see Section 38.5), for which mt = m/2 exactly;
(c) Muonium, an atom composed of a muon and a proton (see Problem 38.59), for which mt = 185.8m.