Obtain the first Bohr’s radius and the ground state energy of a muonic hydrogen atom [i.e., an atom in which a negatively charged muon (μ) of mass about 207me orbits around a proton].

Given: Mass of negatively charged muon mμ = 207me

The Bohr’s radius is given by the relation:


re (1/mc)


Energy of ground state electronic hydrogen atom Ee m


The value of the first Bohr orbit is given as re = 0.53A


Converting into metres, re =0.53 × 10-10m


Let us consider rμ is the radius of muonic hydrogen atom


At equilibrium


mμ rμ = me re


207me × rμ = me re


rμ = (0.53 × 10-10m)/207


rμ =2.56 × 10-13m


The ratio of the energies is given as:


Ee/Eμ = me/mμ = me/207me


We get


Eμ = 207EE


Substituting the value of energy, we get


Eμ = 207 × (-13.6)


Eμ =-2.81 keV


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