11 mark
Tau Ceti is a main-sequence star a little smaller than the Sun. In its core, hydrogen is converted to helium by a series of fusion reactions. What is this series of reactions called?
Stellar Physics · Practice Test A
Advanced Higher Physics · Stellar Physics
Practice Test A
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.
21 mark
Four stars, A, B, C and D, are marked on the H-R diagram. Which star is a red giant?
31 mark
A star like the Sun spends most of its life on the main sequence. What change happens in its core at the point when it leaves the main sequence?
41 mark
As a star like the Sun becomes a red giant, its diameter increases. Which statement explains this?
51 mark
Every main-sequence star ends as a white dwarf, a neutron star or a black hole. Which property of the star decides which one?
Core
13 marksThe demand of the real test — one rearrangement, one conversion or one intermediate step.
66 marks
Antares is a red supergiant in the constellation Scorpius. It is 5.3 × 10¹⁸ m from Earth. Its apparent brightness is 8.5 × 10⁻⁸ W m⁻².
(a) Calculate the luminosity of Antares.3
(b) The radius of Antares is 4.7 × 10¹¹ m. Calculate the surface temperature of Antares.3
77 marks
Tau Ceti is a Sun-like star. Its surface temperature is 5340 K and its radius is 5.52 × 10⁸ m.
(a) Calculate the luminosity of Tau Ceti.3
(b) Tau Ceti is 11.9 light-years from Earth. Determine the apparent brightness of Tau Ceti seen from Earth.4
Push
7 marksTwo or more steps, an unfamiliar context, and a judgement to justify.
82 marks
Star X is marked on the H-R diagram. The dashed lines join stars that have the same radius.
(a) State the type of star X.1
(b) Use the diagram to estimate the radius of star X, in solar radii.1
92 marks
Deneb and Mu Cephei are both supergiants. Their luminosities are about the same. Deneb has a surface temperature of 8.5 × 10³ K. Mu Cephei has a surface temperature of 3.8 × 10³ K.
State whether the radius of Mu Cephei is greater than, less than or equal to the radius of Deneb. Justify your answer.2
103 marks
A star's spectrum can be approximated as a black-body spectrum. The surface temperatures of four stars are: the Sun, 5800 K; Vega, 9600 K; 40 Eridani B, 16 500 K; Mu Cephei, 3.8 × 10³ K. The black-body spectra of the four stars are shown below.
By considering the peak wavelength of each spectrum, match each star to its spectrum. Write each star and its spectrum letter in your jotter.3
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.