JEE Main201910 Apr 2019Evening ShiftPhysicsAtomic PhysicsActual
In L i + + ,electron in first Bohr orbit is excited to a level by a radiation of wavelength λ .When the ion gets de excited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of λ ? (Given: h = 6.63 × 10 - 34 J s ; c = 3 × 10 8 m s - 1 )
Options
- A10.8 n m
- B9.4 n m
- C11.4 n m
- D12.3 n m
Correct answer
A. 10.8 n m
Step-by-step solution
Total Number of possible spectral lines that can be emmited when atom de-excites from state n   to groundstate is C 2 n ∴   n C 2 = 6 ⇒ n ( n - 1 ) 2 = 6 ⇒ n = 4 1 λ = R   z 2 1 1 2 - 1 4 2 = 1.097 × 10 7 × 9 × 1 - 1 16 ⇒ λ = 10.8   n m