Physics; Energy Level Help?
Which photon energy could be absorbed by a hydrogen atom that is in the n = 2 state?
1) 1.51 eV
2) 1.89 eV
3) 2.1 eV
4) 2.4 eV
Well I know the answer is 1) 1.51 eV but I don't understand how to get it.. any help would be awesome.
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Verified answer
The energy levels in a hydrogen atom are (En = -13.6/n^2)
E1 = -13.6eV
E2 = -3.4eV
E3 = -1.51eV
E4 = -0.85eV
E5 = -0.054eV
Now the electron in the 2nd level can only absorb photons with energy that equal the difference between levels
So from n = 2 to 3 the energy difference is 1.89eV
from n = 2 to n = 4 the energy difference is 2.51eV
So of the above mentioned energies only the 1.89eV can be absorbed by the electron
Answer is 2) 1.89eV
Once it absorbs this energy the electron will be in n = 3 where its energy is -1.51eV