IB Physics HL E.1.4 Atomic transitions Question Bank

Practise IB Physics SL/HL E.1.4 by applying atomic transitions concepts to exam-style physics questions.

Exam points

identify the relevant physical quantity, model or diagram
apply the correct equation and units to the evidence
justify the result using conservation laws, fields or energy relationships

[Maximum number: 3]

This question is in two parts.

The energies of the principal energy levels in atomic hydrogen measured in eV are given by the expression

E_{n}=-\frac{13.6}{n^{2}} \text { where } n=1,2,3

The visible lines in the spectrum correspond to electron transitions that end at n=2.

Show that the spectral line of wavelength $\lambda=485 \mathrm{~nm}$ is the result of an electron transition from n=4.

energy difference between levels $=\frac{h c}{\lambda e}=\frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{4.85 \times 10^{-7} \times 1.6 \times 10^{-19}}$ ;
=2.55 eV;
$[3.40-2.55]=0.85=\frac{13.6}{n^{2}}$ to give $n^{2}=16$ ;
n=4;

Marking guidance:

Award [3] for reversed argument.

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E.1.4—Atomic transitions question 1