Grade 12 · Physical Sciences · Physics, Paper 1 · CAPS
The Doppler Effect – Grade 12 Physical Sciences (Physics, Paper 1)
What Doppler Effect covers, how it is examined in Physical Sciences Paper 1 (Physics), the 4 sections to study and how long it takes – plus live online lessons when you get stuck.
- Study sections
- 4
- Exam-style questions
- 9
- Marks of practice
- 73
- Study time
- ≈ 3 h 15 min
What it covers
The Doppler effect explains why a siren sounds higher as it approaches and lower as it moves away. You use the Doppler equation for a moving source or a moving listener, explain the change in frequency with wavefront diagrams, and work backwards to find an unknown speed. The topic also covers uses in medicine, such as ultrasound measurement of blood flow, and the red shift of light from distant galaxies, which tells us the universe is getting bigger.
How it is examined
- Paper
- Physical Sciences Paper 1 (Physics) – Friday 30 October 2026, 09:00 (3 hours, 150 marks)
- Weighting
- Waves, sound and light ≈ 15/150 (Doppler typically ≈ 10–13 marks, plus one or two MCQs)
- Questions
- In a typical paper you will find it in Question 6 of Physical Sciences Paper 1 (Physics), with multiple-choice items in Question 1 as well.
Question numbers and mark splits are typical, not fixed – they vary a little from year to year.
Sections to study
- Sound waves and what the Doppler effect is20 min
- The Doppler equation: moving source25 min
- Moving listener and finding unknown speeds25 min
- Applications: medicine, red shift and the expanding universe25 min
Study time
| Notes and worked examples4 sections | 1 h 35 min |
|---|---|
| Exam-style questions9 questions · 73 marks × 1,2 min per mark | 1 h 30 min |
| Topic quiz | 10 min |
| Total | ≈ 3 h 15 min |
Physical Sciences Paper 1 (Physics) is written on Friday 30 October 2026 at 09:00.
What you get in the portal
- 9 exam-style questions on Doppler Effect (73 marks in total), each with a full marking memo
- Worked examples with diagrams and step-by-step calculations for each of the 4 sections
- Tutor notes added to sections and questions – for the whole class or just for you
- A topic quiz, mock papers and a study plan that counts down to Physical Sciences Paper 1 (Physics)
Notes, worked examples, questions and memos open once the tutor approves your account – usually with your first confirmed lesson.
Stuck on Doppler Effect? Book a one-on-one lesson.
R250 per hour – 60, 90 or 120 minutes, online from anywhere in South Africa. Pick Doppler Effect as your topic; you pay by EFT only after the tutor confirms.
Related Physics P1 topics
- Electrostatics
- Electric Circuits
- Electrodynamics: Generators, Motors and AC
- Photoelectric Effect and Spectra
All Grade 12 Physical Sciences topics, weighting and study time
Questions about Doppler Effect
How many marks is Doppler Effect worth in the matric exam?
In Physical Sciences Paper 1 (Physics) (3 hours, 150 marks) the usual weighting is: Waves, sound and light ≈ 15/150 (Doppler typically ≈ 10–13 marks, plus one or two MCQs). In a typical paper you will find it in Question 6 of Physical Sciences Paper 1 (Physics), with multiple-choice items in Question 1 as well. The exact marks change a little from year to year.
How long does it take to study Doppler Effect?
About 3 h 15 min: 1 h 35 min for the notes and worked examples in its 4 sections, 1 h 30 min for the 9 exam-style questions (73 marks) at exam pace of 1,2 minutes per mark, and a 10-minute quiz.
When is the Physical Sciences Paper 1 (Physics) exam in 2026?
Physical Sciences Paper 1 (Physics) is written on Friday 30 October 2026 at 09:00 and lasts 3 hours (150 marks), according to the DBE’s 2026 NSC timetable. Confirm the date with your school, because the DBE can amend the timetable.
Can I get online lessons for Doppler Effect?
Yes. Create a free account in the Adventuity portal, request a one-on-one online lesson of 60, 90 or 120 minutes (or a seat in a group class) and choose Doppler Effect as your topic. You pay by EFT only after the tutor confirms the booking.