IB Physics HL B 1 14 Black Body Radiation Questions

Practise IB Physics HL B.1.14 by combining Stefan–Boltzmann ratios with radius, temperature, spectra and emissivity to analyse black-body radiation from stars.

Exam points

Apply the Stefan–Boltzmann law L = σAT⁴ to black-body emission from a surface.
Relate emitted electromagnetic power to surface area, absolute temperature and the fourth-power dependence using complete evidence.

[Maximum number: 1]

Star A is a main sequence star.

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

Table for Question IB Physics HL B 1 14 Black Body Radiation Questions question 1 — IB Physics HL

Show that the luminosity of Star A is about half that of the Sun.

$\frac{L_{A}}{L_{S}}=\left(\frac{0.9 R_{s}}{R_{s}}\right)^{2}\left(\frac{5200}{5800}\right)^{4}=0.52$

Must see full substitution OR answer to 2 (or more) significant figures.

Allow the reverse fraction, leading to 1.92.

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IB Physics HL B 1 14 Black Body Radiation Questions question 1