NTA Abhyas JEE Main2020PhysicsAtomic PhysicsPractice
The wavelength of the first spectral line in the Balmer series of the hydrogen atom is 6561 A ∘ . The wavelength of the second spectral line in the Balmer series of singly ionized helium atom is
Options
- A1215   A ∘
- B1640   A ∘
- C2430   A ∘
- D4687   A ∘
Correct answer
A. 1215   A ∘
Step-by-step solution
For hydrogen or hydrogen type atoms 1 λ = R Z 2 1 n f 2 - 1 n i 2 In the transition from n i →   n f ∴                           λ   ∝   1 Z 2 1 n f 2 - 1 n i 2 ∴                           λ 2 λ 1 =   Z 1 2 1 n f 2 - 1 n i 2 1 Z 2 2 1 n f 2 - 1 n i 2 2