 #1
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Homework Statement
Homework Equations
ΔE = hf
The Attempt at a Solution
f = ΔE/h = ##k\left [ \frac{1}{(n1)^2}  \frac{1}{n^2} \right ]##
= ## \frac{k(2n1)}{n^2(n1)^2}##
= ## \frac{k}{n^4}(2n1)(1\frac{1}{n})^{2}##
= ## \frac{2kn}{n^4}(1\frac{1}{2n})(1+\frac{2}{n} +## higher powers ## )##
≈ ## \frac{2k}{n^3}(1\frac{3}{2n}) ## . If I neglect the second term in the bracket , then I get option 3) , but I doubt whether I can do that because I need to retain atleast first order terms .
how should I proceed ?
Any help is appreciated .
Thanks
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