Unit 5: Nuclear and Quantum Physics
Topic 5.5: Fusion and Stars Questions
Practice 20 exam-style questions for IB Physics SL Topic 5.5. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.
1Identify1 mark
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A main-sequence star leaves the main sequence to become a red giant. What happens to its surface temperature and luminosity?
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Unlock Question2Calculate1 mark
2025
The parallax angle of a nearby star is 0.20 arc-seconds. How far away is it?
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A star is very small and dense, and glows white-hot but faintly.
Suggest its evolutionary stage.
Suggest its evolutionary stage.
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In which region of an HR diagram are white dwarfs found?
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2026
Describe the two pressures acting on a layer inside a main-sequence star.
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In d = 1/p, which gives d in parsecs, state the unit in which p must be.
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A star begins with 12 times the Sun's mass. What object is it most likely to leave behind?
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A star's luminosity and temperature place it on the diagonal band of the HR diagram.
Suggest its evolutionary stage.
Suggest its evolutionary stage.
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State what happens to the amount of helium in the Sun's core during its main-sequence life.
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Why must the core of a star be at a very high temperature for fusion?
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Lifetime estimates treat a star's hydrogen in a simplified way.
State one such simplification.
State one such simplification.
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The parallax of a star is 0.25 arc-seconds. How far away is it, in metres? (1 pc = 3.1 × 1016 m)
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A main-sequence star of about 25 solar masses evolves. Which sequence follows?
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Unlock Question15Show that1 mark
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An infrared telescope finds a cool star radiates most strongly at 1.2 µm.
Show, with Wien's law, that the star is at about 2400 K.
Show, with Wien's law, that the star is at about 2400 K.
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Most of a star's light comes out near 290 nm, where its intensity is greatest.
Show, using Wien's law, that the star is at roughly 10 000 K.
Show, using Wien's law, that the star is at roughly 10 000 K.
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Sunlight is most intense at a wavelength of 500 nm.
Use Wien's law to show that the Sun is close to 5800 K at the surface.
Use Wien's law to show that the Sun is close to 5800 K at the surface.
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Unlock Question18Suggest1 mark
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A star is huge, cool and very luminous.
Suggest its evolutionary stage.
Suggest its evolutionary stage.
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Star F is half as wide as the Sun but hotter: 8000 K against the Sun's 5800 K.
Show that its power output is close to 0.9 L☉.
Show that its power output is close to 0.9 L☉.
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Unlock Question20Identify1 mark
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Which star is most likely to be a white dwarf?
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