Energy Levels & Spectral Series Challenge
25 NEET-standard questions on the energy levels of hydrogen, excitation and ionisation, and the Lyman, Balmer, Paschen, Brackett and Pfund series. Answer each one. If you get it wrong, Vidya Ma’am explains it with an animated movie you can control, a slider to play with, and a step-by-step solution. Then try again.
NCERT Physics XII Part II · Ch. 12 · pp. 299–300Keys: A–D or 1–4 to answer
🧠 Formula memory tricks (open before you start)
Energy levelsEₙ = −13.6/n² eVE₁ = −13.6, E₂ = −3.40, E₃ = −1.51, E₄ = −0.85
Ionisation energy13.6/n² eV13.6 eV from n = 1, 3.40 eV from n = 2
Photon from a jumphν = Eᵢ − E_fλ(nm) = 1240 / ΔE(eV)
Rydberg formula1/λ = R(1/n_f² − 1/nᵢ²)R = 1.097×10⁷ m⁻¹
Final levelsLyman 1 · Balmer 2 · Paschen 3 · Brackett 4 · Pfund 5Lyman UV, Balmer visible, the rest infrared
Longest and shortestLongest: nᵢ = n_f + 1. Shortest (limit): nᵢ = ∞, λ = n_f²/R.
Number of linesn(n − 1)/2n = 5 gives 10 lines
Photon vs electronA photon must match a gap exactly (or exceed the binding energy). A colliding electron can give part of its energy.
right first tryfixed after explanationstill to fix
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