MHT CET2019Morning ShiftPhysicsAtomic PhysicsActual
In hydrogen emission spectrum, for any series, the principal quantum number is n. Corresponding maximum wavelength λ is (R = Rydberg’s constant)
Options
- AR 2 n + 1 n 2 n + 1
- Bn 2 n + 1 2 R 2 n + 1
- Cn 2 n + 1 R 2 n + 1
- DR 2 n + 1 n 2 n + 1 2
Correct answer
B. n 2 n + 1 2 R 2 n + 1
Step-by-step solution
In hydrogen emission spectrum, wavelength is given by 1 λ = R 1 n 1 2 - 1 n 2 2 For maximum wavelength of any principal quantum number n, n 1 = n a n d n 2 = n + 1 ∴ 1 λ m a x = R 1 n 2 - 1 n + 1 2 = R n + 1 2 - n 2 n 2 n + 1 2 = R n 2 + 2 n + 1 - n 2 n 2 n + 1 2 1 λ m a x = R 2 2 n + 1 n 2 n + 1 2 ∴ λ m a x = n 2 n + 1 2 R 2 n + 1