CAIE A-Level Physics 25.2.3 Estimating Stellar Radius

Practise combining Wien’s displacement and Stefan–Boltzmann laws to estimate a star’s surface temperature, luminosity or radius from observed data.

Exam points

combine Wien’s displacement law and the Stefan–Boltzmann law to estimate a star’s radius

[Maximum number: 2]

The radiant flux intensity of the radiation from the star in (b) is $2.52 \times 10^{-8} \mathrm{Wm}^{-2}$ when observed at a distance of $4.16 \times 10^{16} \mathrm{~m}$ from the star.

Determine the radius of the star.
radius = m

$\begin{aligned} L=4 \pi \sigma r^{2} T^{4} 5.48 \times 10^{26}=4 \pi \times 5.67 \times 10^{-8} \times r^{2} \times 6980^{4} \end{aligned}$

C1

$r=5.69 \times 10^{8} \mathrm{~m}$

A1

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25.2.3—Wien’s displacement law and the Stefan–Boltzmann law to estimate the radius question 1