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Asked in GSEB Board July 2023 · Spectral series and wavelengths
Idea: in the Bohr model the energy of the nth level is Eₙ=-(me⁴)/(8ε₀²h²n²).
A jump from n₂ down to n₁ emits a photon with (hc)/λ=E_n₂-E_n₁=(me⁴)/(8ε₀²h²)(1/(n₁²)-1/(n₂²)).
Dividing by hc: 1/λ=(me⁴)/(8ε₀²h³c)(1/(n₁²)-1/(n₂²)).
Comparing with 1/λ=R(1/(n₁²)-1/(n₂²)) gives R=(me⁴)/(8ε₀²h³c).
Putting in the constants gives R≈1.097×10⁷ m⁻¹, the measured value.
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