Assuming f to be the frequency of the electromagnetic wave corresponding to the first line in Balmer series, the frequency of the immediate next line is

Step-by-step solution

For Balmer series, n f =2 and n i =3,4,5,.... Frequency, of 1st spectral line of Balmer series f = R Z 2 c 1 2 2 - 1 3 2 or f = R Z 2 c × 5 36 ...(i) Frequency, of 2nd spectral line of Balmer series f ’ = R Z 2 c 1 2 2 - 1 4 2 or f ′ = R Z 2 c × 3 16 ....(ii) Form eqs. (i) and (ii), we have f f ′ = 20 27 ∴ f ′ = 27 20 f = 1.35 f