The value of ni if the observed wavelength is 657 nm is

Question

The value of ni if the observed wavelength is 657 nm is

a. 4

b. 2

c. 5

d. 3

I think the answer is b. 2, since 657 nm is part of the Balmer Series (to n=2)

Answer 1

The answer should be (d), i.e. n_i = 3. The Balmer series is for electrons in excited states transitioning to the n = 2, so 2 is n_f not n_i. The initial n would be 3 because 3->2 has a greater wavelength than 4->2 which is greater than 5->2 which is greater than 6->2

The associated wavelengths in the Balmer series are as follows:

3 -> 2 = 657 nm

4 -> 2 = 486 nm

5 -> 2 = 434 nm

6 -> 2 = 410 nm