11 mark
Four regions of the H-R diagram are labelled P, Q, R and S. Stars like the Sun fuse hydrogen in their cores. In which region are these stars found?
Stellar Physics · Practice Test B
Advanced Higher Physics · Stellar Physics
Practice Test B
Answer everything, then mark it in one go.
25marks
35 minsuggested
10questions
Have your jotter and a pen beside you. Do every calculation in your jotter, showing each line exactly as you would in the exam. This page asks you only for the relationship you used and your final answer with its unit. Written answers are marked by you, against the scheme.
Powers of ten can be typed any way you like — 2.5e4, 2.5*10^4, 2.5x10^4 or 2.5 × 10⁴ are all read the same.
Nothing is timed and nothing is sent anywhere — your answers stay on this device, so you can close the tab and come back.
Relationships you may need
| Quantity | Relationship |
|---|---|
| Power per unit area | P / A = σT4 |
| Luminosity | L = 4πr2σT4 |
| Apparent brightness | b = L / (4πd2) |
Data sheet — the values this test needs
| Quantity | Symbol | Value |
|---|---|---|
| Stefan–Boltzmann constant | σ | 5.67 × 10⁻⁸ W m⁻² K⁻⁴ |
| Speed of light in a vacuum | c | 3.00 × 10⁸ m s⁻¹ |
The light-year is not on the data sheet. Convert it yourself: 1 ly = 3.00 × 10⁸ × 365.25 × 24 × 60 × 60 m. Using 365 days is accepted too.
Working goes in your jotter. On this page you give the relationship and the final answer only — the mark scheme at the end shows the substitution you should have written down.
Warm-up
5 marksEveryone should aim for full marks here. One step, no rearranging.
22 marks
The proton–proton chain in the core of a star has three stages.
Stage 1: ¹₁H + ¹₁H → ²₁H + ⁰₊₁e + ν
Stage 2: ²₁H + ¹₁H → ³₂He + Z
Stage 3: ³₂He + ³₂He → X + ¹₁H + ¹₁H
Identify the particles or radiation represented by X and Z.2
31 mark
Two stars have the same surface temperature. The radius of star P is three times the radius of star Q. What is the luminosity of P divided by the luminosity of Q?
41 mark
Two stars have the same luminosity. Star R is twice as far from Earth as star S. What is the apparent brightness of R divided by the apparent brightness of S?
Core
13 marksThe demand of the real test — one rearrangement, one conversion or one intermediate step.
56 marks
Barnard's Star is a red dwarf on the main sequence. It is one of the closest stars to the Sun. Its surface temperature is 3130 K and its luminosity is 1.35 × 10²⁴ W.
(a) Calculate the power per unit area emitted from the surface of Barnard's Star.3
(b) Calculate the radius of Barnard's Star.3
65 marks
Aldebaran is an orange giant in the constellation Taurus. It is 65 ly from Earth. It has a radius of 3.1 × 10¹⁰ m. Its apparent brightness is 3.6 × 10⁻⁸ W m⁻².
Determine the surface temperature of Aldebaran.5
72 marks
Canopus is the second-brightest star in the night sky. It is 2.9 × 10¹⁸ m from Earth. Its apparent brightness is 3.9 × 10⁻⁸ W m⁻².
Show that the luminosity of Canopus is 4.1 × 10³⁰ W. Write your working in your jotter.2
Push
7 marksTwo or more steps, an unfamiliar context, and a judgement to justify.
83 marks
A group of pupils are talking about the stars Capella and Regulus.
- Pupil 1: "Why does Regulus look blue-white, while Capella looks yellow?"
- Pupil 2: "Capella looks brighter than Regulus, so it must be closer to us."
- Pupil 3: "Two stars that look close together in the sky must be close together in space."
- Pupil 4: "A star's colour tells you nothing about its temperature."
93 marks
Every star ends its life as a white dwarf, a neutron star or a black hole. Using your knowledge of physics, comment on the similarities and differences in how stars evolve into these three objects.
101 mark
Proxima Centauri is a small red dwarf. Stars like it stay on the main sequence for thousands of billions of years.
Scientists know the mass of stars like this. Suggest why they have still not observed what happens to these stars at the end of their lives.1
Your result
0out of 25
0%percentage
—indicative band
Bands are indicative only — they are a guide to where you are, not a grade.
Sources & credits: questions are adapted from Advanced Higher Physics past papers, reproduced and adapted for educational use — past papers and marking instructions © Qualifications Scotland (SQA). Stars, numbers and contexts have been changed, and questions marked as original were written for this site. H-R diagrams and spectra drawn for this site © R Stewart, 2026. R Stewart - September 2026.