JEE MainPhysicsAtomic Physics
Photons from two different transitions in the Lyman series of hydrogen are incident sequentially on the same metal surface. The first member of the Lyman series has wavelength and produces a stopping potential V₀ . The second member of the Lyman series produces a stopping potential V₁ . The difference in stopping potentials (V₁ - V₀) is
Options
- A32hc 27e
- B5hc 32e
- C5hc 27e
- D27hc 32e
Correct answer
C. 5hc 27e
Step-by-step solution
For the Lyman series, the transitions terminate at n₁ = 1 . For the first member ( n=2 n=1 ): 1 = R ( 1 1^2 - 1 2^2 ) = 3R 4 R = 4 3 For the second member ( n=3 n=1 ), let the wavelength be ₂ : 1 ₂ = R ( 1 1^2 - 1 3^2 ) = 8R 9 Substituting R = 4 3 into the above equation: 1 ₂ = 8 9 ( 4 3 ) = 32 27 According to Einstein's photoelectric equation, the stopping potential V is given by eV = hc - W , where W is the work function. For the first member: eV₀ = hc - W For the second member: eV₁ = hc ₂ - W Subtracting the fir