DP Physics (last assessment 2024)

Question 18N.3.HL.TZ0.18a.iii

a.iii.

[Maximum mark: 2]

18N.3.HL.TZ0.18a.iii

The surface temperature of the star Epsilon Indi is 4600 K.

(a.iii)

The following data are available for the Sun.

Surface temperature = 5800 K

Luminosity = ${L_ \odot }$

Mass = ${M_ \odot }$

Radius = ${R_ \odot }$

Epsilon Indi has a radius of 0.73 ${R_ \odot }$ . Show that the luminosity of Epsilon Indi is 0.2 ${L_ \odot }$ .

[2]

Markscheme

$\frac{L}{{{L_ \odot }}} = {\left( {\frac{{0.73{R_ \odot }}}{{{R_ \odot }}}} \right)^2} \times {\left( {\frac{{4600}}{{5800}}} \right)^4}$ ✔

L = 0.211 ${L_ \odot }$ ✔

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