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# What is the wavelength of a photon that will excite an electron from n=3 to n=5 in a hydrogen atom?

What is the wavelength of a photon that will excite an electron from n=3 to n=5 in a hydrogen atom?

Use R∞=2.179×10−18J for the hydrogen atom Rydberg constant.

Use h=6.626×10−34 Js for Planck's constant.

Use c=2.998×108ms for the speed of light.

### 2 Answers

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- Anonymous6 months agoFavorite Answer
change in energy = R(1/3² - 1/5²) = 1.55e-19 J

and

change in energy = hv / λ

so

λ = hv / change in energy = 6.626e−34J·s * 2.998e8m/s / 1.55e-19J

λ = 1.282e-6 m = 1.282 µm = 1282 nm

- VamanLv 76 months ago
The energy = R(1/3^2-1/5^2)=R/3^2 5^2(5^2-3^2)=R 16/(9*25)=1.54*10^(-18).

frequency= 1.54*10^(-18)/6.6 *10^34=10^(16)*2.3*10^(-2)=2.3*10^(14).

Wave length= 3*10^(8)/2.3/10^(14)=1.3*10^(-6) m

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