How to Answer IGCSE Physics Paper 4 (Extended Theory)

Use this guide to prepare for IGCSE Physics Paper 4 (Extended Theory), the paper that covers the full Extended syllabus.

Paper 4 structure

• Duration: 1 hour 15 minutes (75 minutes).
• Total marks: 80.
• Format: structured questions requiring written answers, calculations and diagrams.
• All six topics are covered, though the balance of subtopics varies between sessions.
• Weighting: approximately 1 minute per mark.

Reading time strategy

Spend the first 2 to 3 minutes scanning the paper. Identify:

• Questions on your strongest topics (do these first to bank marks).
• The longest question (usually 8 to 10 marks, found near the end).
• Any unfamiliar contexts (these are often ‘suggest’ or ‘explain’ questions worth exploring after the easier ones).

Structured question technique

Most Paper 4 questions have parts (a), (b), (c), etc., with increasing difficulty.

• Part (a) is usually ‘state’ or ‘define’: quick recall, 1 to 2 marks.
• Part (b) often involves a calculation or diagram: 2 to 4 marks.
• Part (c) or (d) is usually ‘explain’ or ‘suggest’: 3 to 6 marks.

Work through each part in order. Later parts sometimes build on earlier ones, so a correct answer to (a) can guide your thinking for (c).

Calculation strategy

1. Write the formula.
2. Substitute with units.
3. Show the rearrangement if needed.
4. State the final answer with the correct unit.
5. Check the number of significant figures matches the data.

For multi-step calculations, clearly label each step. If part (b) uses the answer from part (a), write “using value from (a)” so the examiner knows you are carrying forward correctly.

Extended-response questions (4 to 6 marks)

These questions ask ‘explain’, ‘describe’ or ‘discuss’. They require connected reasoning, not bullet points.

Structure your answer:

1. State the physics principle.
2. Apply it to the specific situation in the question.
3. State the outcome or conclusion.

Write one idea per sentence. Use physics vocabulary from the syllabus.

Topics that appear most frequently

Based on past paper analysis, these topics carry the most marks:

• Forces, motion and energy calculations (Topic 1)
• Circuit calculations, series and parallel (Topic 4)
• Waves, reflection and refraction (Topic 3)
• Thermal energy transfer (Topic 2)
• Radioactivity and half-life (Topic 5)

End-of-paper checklist

Before handing in your paper:

1. Have you attempted every question?
2. Have you included units in every calculation answer?
3. Have you labelled every diagram?
4. Have you answered the question that was asked (not a different one)?
5. Are your explanations specific to the scenario given?