IB Physics SL C.5.3 Light Doppler approximation Question Bank

Practise IB Physics SL/HL C.5.3 by applying light doppler approximation 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: 2]

Star A is a main sequence star.

The data for Star A and the Sun are given in a table.

Table for Question C.5.3—Light Doppler approximation question 1 — IB Physics SL

Determine the speed, in $\mathrm{km} \mathrm{s}^{-1}$ , of Star A relative to Earth.

$\begin{aligned} v=\frac{\Delta \lambda}{\lambda} c=\frac{0.007}{100} \times 3 \times 10^{8}=21000 21 \mathrm{~km} \mathrm{~s}^{-1} \end{aligned}$

Allow ECF for MP2.

Do not award MP1 for use of the Doppler formulas for sound and mechanical waves.

[2]

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C.5.3—Light Doppler approximation question 1