NEET 2016 Phase 2 · PhysicsRydberg formulaPrevious Year Question
If an electron in a hydrogen atom jumps from the 3rd orbit to the 2nd orbit, it emits a photon of wavelength λ. When it jumps from the 4th orbit to the 3rd orbit, the corresponding wavelength of the photon will be:
Answer: (C) 20/7 λ. Answer: (c) 20/7 λ Solution: 3→2: 1/λ = R(1/2² − 1/3²) = R(1/4 − 1/9) = R(5/36).
- A.16/25 λ
- B.9/16 λ
- C.20/7 λ✓
- D.20/13 λ
Correct Answer
(C) 20/7 λ
Solution & Explanation
Answer: (c) 20/7 λ Solution: 3→2: 1/λ = R(1/2² − 1/3²) = R(1/4 − 1/9) = R(5/36). 4→3: 1/λ' = R(1/3² − 1/4²) = R(1/9 − 1/16) = R(7/144). Ratio λ'/λ = (1/λ)/(1/λ') = (5/36)/(7/144) = (5/36)×(144/7) = 720/252 = 20/7. Therefore λ' = (20/7)λ.
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