If wavelength of the first line of the Paschen series of hydrogen atom is 720 nm , then the wavelength of the second line of this series is _______ nm . (Nearest integer)

Step-by-step solution

Paschen series are spectral lines coming to n = 3 1 st line of Paschen series makes a transition from, 4 → 3 So, 2 nd line of Paschen series makes a transition from, 5 → 3 We know that, 1 λ = R 1 n 1 2 - 1 n 2 2 Z 2 For 1 st line, 1 λ = R 1 ( 3 ) 2 - 1 ( 4 ) 2 Z 2 and for 2 nd line, 1 λ ' = R 1 ( 3 ) 2 - 1 ( 5 ) 2 Z 2 or 1 λ 1 λ ' = R 7 9 × 16 Z 2 R 16 9 × 25 Z 2 Given, λ = 720   nm or 1 720 1 λ ' = 175 256 or λ ' 720 = 175 256 or &#