E=-hR/n^2 v. Rydberg forumla

[Seohyun Park 1L]

For 6th edition, 1.15, the problem asks to find the principal quantum number of a certain wavelength. Using Rydberg formula, I was able to find the right value of n2 assuming n1=1, but when I tried using E=-hR/n^2 and subtracting the energy level for n1 from n2, I failed to get the right n2 value. Is there a reason why? Shouldn't both methods technically work?

[marisaimbroane1J]

Make sure you set the final and initial calculations equal to a negative energy. The E is emitted and therefore negative. I'm not sure if that will give you the right answer, but try starting with that and see if it works.