n1=3(always)
wavelength=1010/10^9 m=1.01/10^6 m (converted into metre)
n2=?
we have a formula
1/wavelength= 1.09677x10^7[(1/n1^2)-(1/n2^2)]
10^6/1.01= 1.01677x10^7[1/9-1/n2^2]
(9.174x10^5)/(1.09677x10^7)= 1/9-1/n2^2
0.08365=0.1111-1/n2^2
1/n2^2=0.1111-0.08365
n2^2=1/0.02746
n2=6
means this electon's ground(original) state was n1=3.After gaining energy it went to n2=6 and when it came back to n1=3,it removed that energy which was seen in the form of spectral lines and these lines had a wavelength of 1010nm.
the lines are observed in infrared region of the electromagnetic spectrum.
