IB Physics HL E.1.11 Bohr angular momentum Question Bank

Practise IB Physics HL E.1.11 by applying bohr angular momentum 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: 4]

(a)

Bohr modified the Rutherford model by introducing the condition $m v r=n \frac{h}{2 \pi}$ .

Outline the reason for this modification.

[ 3 ]

the electrons accelerate and so radiate energy they would therefore spiral into the nucleus/atoms would be unstable electrons have discrete/only certain energy levels the only orbits where electrons do not radiate are those that satisfy the Bohr condition $<m v r=n \frac{h}{2 \pi}>$

3 max

(b)

Calculate the electron's orbital radius in (c)(ii).

[ 1 ]

$\begin{aligned} <r=\frac{\left(6.63 \times 10^{-34}\right)^{2}}{4 \pi^{2} \times 8.99 \times 10^{9} \times 9.11 \times 10^{-31} \times\left(1.6 \times 10^{-19}\right)^{2}} \text { 》 } r=5.3 \times 10^{-11}<\mathrm{m} \gg \end{aligned}$

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E.1.11 (HL)—Bohr angular momentum question 1

Question (a)

Question (b)