the necessary centripetal force for the electron to revolve is beibg provided in the form of the electrostatic force of attraction between the electron and the protons in the nucleus.
u need to multipy the charge on the proton with the atomic no." Z" to get the charge on the nucleus during solving the numericals.
v =( Z e2/4IIE0 m r)1/2
plz rate if use ful and correct me if im wrong