IB Physics HL · 2025 to 2026
5.5 Fusion and stars
38 past paper questions from 10 papers across 3 exam sessions. See what repeats, then practise the same skills with AI marking.
Starter set across the most-tested skills, with AI marking and model answers.
HL archive · 2025 to 2026
5.5 Fusion and stars
Latest exam session: May 2026
- questions
- 38
- questions
- papers
- 10
- papers
- exam sessions
- 3
- exam sessions
- micro-topics
- 4
Micro-topics in 5.5 Fusion and stars
In syllabus order. The ring is the share of papers each appears in.
5.5.1
Nuclear fusion and stellar equilibrium
22 questions · in 67% of papersAppears in 8 of the 12 Physics HL papers analysed (67%), at least once each.
Frequently testedlast May 26 P2 TZ3
5.5.2
Stellar lifetime and mass loss
1 question · in 8% of papersAppears in 1 of the 12 Physics HL papers analysed (8%), at least once each.
Occasionallast May 25 P2 TZ2
5.5.3
Luminosity, apparent brightness and distance
8 questions · in 50% of papersAppears in 6 of the 12 Physics HL papers analysed (50%), at least once each.
Frequently testedlast May 26 P1 TZ2
5.5.5
The Hertzsprung-Russell diagram and stellar classification
7 questions · in 42% of papersAppears in 5 of the 12 Physics HL papers analysed (42%), at least once each.
Frequently testedlast May 26 P2 TZ3
Exam pattern
How often each micro-topic has been examined, year by year. Each label is explained under the grid.
Does it repeat?
Questions per year for each micro-topic.
fewermore
| Micro-topic | 2025 | 2026 |
|---|---|---|
| 14Nuclear fusion and stellar equilibrium, 2025: 14 questions | 8Nuclear fusion and stellar equilibrium, 2026: 8 questions | |
| 7Luminosity, apparent brightness and distance, 2025: 7 questions | 1Luminosity, apparent brightness and distance, 2026: 1 question | |
| 5The Hertzsprung-Russell diagram and stellar classification, 2025: 5 questions | 2The Hertzsprung-Russell diagram and stellar classification, 2026: 2 questions | |
| 1Stellar lifetime and mass loss, 2025: 1 question | ·Stellar lifetime and mass loss, 2026: 0 questions |
- Frequently testedin at least a quarter of all papers, and still appearing in the last two years
- Occasionalin about one paper in ten
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Questions on 5.5 Fusion and stars, by exam session
Which papers asked about 5.5 Fusion and stars, and which question numbers. Open a paper to see them highlighted.
May 2026
6 questions across 3 papers
May 2025
9 questions across 5 papers
Specimen 2025
5 questions across 2 papers
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Frequently asked questions
Short answers about this page.
Which Physics HL exam sessions are covered for 5.5 Fusion and stars?
3 exam sessions from 2025 to 2026, the latest May 2026. Every Paper 1 and 2 in every timezone is read and classified in full, which gives 10 papers in this archive.
Which 5.5 Fusion and stars topic comes up most?
Nuclear fusion and stellar equilibrium (5.5.1): in 67% of papers, last seen May 26 P2 TZ3. Usually "find / solve", worth about 4.8 marks in a paper that includes it.
Can I see the original question and mark scheme?
No. The wording belongs to the IB. You get the citation, the marks, the command term and the skill tested, plus our own matched practice questions with worked answers and AI marking.
What do "banker", "due" and "rising" mean?
Banker: examined in at least one sitting in four and still appearing. Due: regular before, but absent for the last two exam sessions. Rising: clearly more common in the last two years. Our classification of real papers, not an IB statistic.
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