1. The problem statement, all variables and given/known data In a very strong applied field the sodium resonance lines is foudn to have components at 588.5 nm, 589 nm and 590.1 nm. What is the strength of the applied field? 3. The attempt at a solution So I have: 3P_(1/2) --> 3S_(1/2) AND 3P_(3/2) ---> 3S_(1/2) Then I know, for strong magnetic fields: E = (m_l + 2m_s ) B μ_B I found the max change in (m_l + 2m_s ) to be about 2 and the change in E to be hc/∆λ and I know ∆λ is 0.8 nm : If I put all this into the equation I get B to be very large, which is clearly wrong..what Im I doing wrong? Thanks.