99 Percentile Qs Bank for JEE MainPhysicsAtomic Physics
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 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 Substituting the values, we have = ( 6561 ) 1 2 1 2 2 - 1 3 2 2 2 1 2 2 - 1 4 2 = 1215 A ∘