Minimum excitation potential of Bohr's first orbit in hydrogen atom is

Excitation potential = $\frac{\text { Excitation energy }}{e}$

Minimum excitation energy corresponds to excitation from n = 1 to n = 2

∴  Minimum excitation energy in hydrogen atom $=-3.4-(-13.6)=+10.2~eV$ so minimum excitation potential = 10.2 eV.