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QPages 384-386: Q12: HC Verma: Concepts of Physics - Volume 2 Bohr's Model and Physics of the Atom Pages 384-386: Q12 Solution: A hydrogen atom in a state having a binding energy of 0.85 eV…

A hydrogen atom in a state having a binding energy of 0.85 eV makes transition to a state with excitation energy 10.2 eV. a) Identify the quantum numbers nn of the upper and the lower energy states involved in the transition. b) Find the wavelength of the emitted radiation.

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**Answer:** (a) Upper state n = 4, lower state n = 2. (b) Wavelength = 486 nm. **Step-by-Step Explanation:** (a) Binding energy 0.85 eV: En=−0.85⇒13.6/n2=0.85⇒n2=16⇒n=4E_n = -0.85 \Rightarrow 13.6/n^2 = 0.85 \Rightarrow n^2 = 16 \Rightarrow n = 4. Excitation energy 10.2 eV: En=−13.6+10.2=−3.4⇒13.6/n2=3.4⇒n2=4⇒n=2E_n = -13.6 + 10.2 = -3.4 \Rightarrow 13.6/n^2 = 3.4 \Rightarrow n^2 = 4 \Rightarrow n = 2. So the transition is 4 _ 2. (b) 1λ=R(1/22−1/42)=R(1/4−1/16)=3R/16\frac{1}{\lambda} = R(1/2^2 - 1/4^2) = R(1/4 - 1/16) = 3R/16. λ=16/(3×1.097×107)=4.86×10−7\lambda = 16/(3 \times 1.097 \times 10^7) = 4.86 \times 10^{-7} m = 486 nm [citation:3].

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