The Bohr model can be applied to singly ionized helium He+ (Z=2). Using the model, consider the series of lines that is produced when the electron makes a transistion from higher energy levels into the nf = 3 level. Some of the lines in the series lie in the visible region of the spectrum (380 nm - 750 nm). What are the (a)minimum value and (b) maximum value of ni for the energy levels from which the electron makes the transitions corresponding to these lines?