IB Physics SL E.5.7 Stellar radii Question Bank

Practise IB Physics SL/HL E.5.7 by applying stellar radii 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]

The graph shows an incomplete Hertzsprung-Russell (HR) diagram. The position of the Sun and three other stars, A, B and C , are shown.

Figure for Question E.5.7—Stellar radii question 1 — IB Physics SL

$M_{\odot}, R_{\odot}$ and $L_{\odot}$ are the mass, radius and luminosity of the Sun.

Determine the radius of star B in terms of $R_{\odot}$ .

$L_B=L_A=10^6L_{\odot}$ .
$10^6=(R_B/R_{\odot})^2(3.0/6.0)^4$ .
$R_B/R_{\odot}=\sqrt{10^6\times16}=4\times10^3$ .

Award [3] for BCA. Do not allow ECF from MP2 to MP3.

\frac{R_B}{R_\odot}=\sqrt{10^6\times16}=4\times10^3

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E.5.7—Stellar radii question 1