Introduction
IGCSE Physics covers 21 core topics that build from fundamental concepts to complex applications. This comprehensive guide will help you master every topic systematically, using proven strategies that have helped thousands of students achieve A* grades.
Whether you're starting your revision from scratch or fine-tuning your knowledge before exams, this guide provides a clear roadmap. We'll break down each major topic area, highlight examiner expectations, and connect you to targeted practice resources.
Pro Tip: Physics is cumulative. Mastering earlier topics (like forces and motion) makes later topics (like energy and momentum) much easier. Don't skip the fundamentals.
1. Mechanics (Motion, Forces, Energy)
Key Topics You Must Master
- Motion: Distance, displacement, speed, velocity, acceleration
- Forces: Newton's laws, friction, weight vs mass, resultant forces
- Momentum: Conservation, collisions, impulse
- Energy: Work, power, kinetic energy, potential energy, conservation
Common Exam Questions
Expect questions asking you to:
- Calculate acceleration from velocity-time graphs
- Apply F = ma to real-world scenarios (cars, lifts, rockets)
- Solve momentum conservation problems in collisions
- Calculate work done and power in various contexts
Study Strategy
Start with motion graphs. If you can interpret and draw distance-time and velocity-time graphs, you've conquered 30% of mechanics. Practice calculating gradients (for velocity and acceleration) and areas under curves (for distance and displacement).
Examiner Insight: Students often confuse velocity with speed. Remember: velocity is a vector (has direction), speed is a scalar (magnitude only). This distinction is crucial for momentum questions.
Recommended Practice: Work through past papers from 2018-2025, focusing on:
- Paper 2 (Extended): Motion calculations with graphs
- Paper 4: Experimental design for measuring acceleration
- Paper 6: Analyzing motion data and uncertainties
2. Electricity & Magnetism
Core Concepts
- Current, Voltage, Resistance: Ohm's law, V = IR, series and parallel circuits
- Electrical Power: P = IV, P = I²R, energy transfers in circuits
- Magnetism: Magnetic fields, electromagnets, motors, generators
- Electromagnetic Induction: Faraday's law, transformers, AC vs DC
Circuit Analysis Skills
You must be able to:
- Draw and interpret circuit diagrams using correct symbols
- Calculate total resistance in series (R_total = R₁ + R₂) and parallel (1/R_total = 1/R₁ + 1/R₂)
- Apply Kirchhoff's laws (current at junctions, voltage in loops)
- Calculate power dissipation and energy costs
Common Mistake: Students often forget that voltage divides in series circuits but is the same across parallel branches. Master this and you'll ace circuit questions.
Magnetism & Induction
This section is heavily tested in Paper 4 (practical) and Paper 6 (alternative to practical):
- How to investigate factors affecting electromagnet strength
- Explaining motor and generator operation using Fleming's rules
- Transformer calculations: V_p/V_s = N_p/N_s
3. Waves & Optics
Wave Properties
All waves (mechanical and electromagnetic) share these properties:
- Wavelength (λ): Distance between successive crests
- Frequency (f): Number of waves per second (Hz)
- Speed (v): v = fλ (this equation appears in EVERY exam)
- Amplitude: Maximum displacement from equilibrium
Electromagnetic Spectrum
You must memorize the EM spectrum in order (longest to shortest wavelength):
Radio → Microwave → Infrared → Visible → Ultraviolet → X-rays → Gamma rays
For each type, know:
- Typical uses (e.g., microwaves for cooking and communications)
- Dangers (e.g., UV causes skin cancer, X-rays can damage cells)
- Relative wavelengths and frequencies
Light & Optics
- Reflection: Angle of incidence = angle of reflection, image formation in plane mirrors
- Refraction: Bending of light when entering different media, total internal reflection
- Lenses: Converging vs diverging, ray diagrams, magnification
Exam Technique: For ray diagram questions, use a ruler and draw to scale. Examiners award marks for accurate diagrams, not just final answers.
4. Thermal Physics
Temperature vs Heat
This is a crucial distinction many students miss:
- Temperature: Measure of average kinetic energy of particles (°C or K)
- Heat: Energy transferred due to temperature difference (Joules)
Energy Transfer Methods
- Conduction: Through solids via particle collisions (metals are good conductors)
- Convection: Through fluids via bulk movement of particles (hot air rises)
- Radiation: Via electromagnetic waves (no medium needed, works in vacuum)
Key Equations
- Specific heat capacity: E = mcΔT (energy = mass × SHC × temperature change)
- Latent heat: E = mL (energy for phase change without temperature change)
Practice these calculations extensively. They appear in every exam paper, often worth 4-6 marks.
5. Nuclear Physics & Radioactivity
Atomic Structure
- Protons: Positive charge, mass ≈ 1 u, in nucleus
- Neutrons: No charge, mass ≈ 1 u, in nucleus
- Electrons: Negative charge, negligible mass, in shells around nucleus
Types of Radiation
| Type | Nature | Penetration | Ionization |
| Alpha (α) | Helium nucleus (2p, 2n) | Stopped by paper | Highly ionizing |
| Beta (β) | High-speed electron | Stopped by aluminum | Moderately ionizing |
| Gamma (γ) | EM wave | Reduced by thick lead | Weakly ionizing |
Half-Life
The time taken for half of the radioactive nuclei to decay. This is tested in calculation and graph interpretation questions.
Exam Tip: For half-life graphs, mark the y-axis at 50%, 25%, 12.5% of original count. The time intervals between these points are equal (each is one half-life).
Exam Strategy & Mark Scheme Secrets
Paper 2 (Theory - Extended)
- Time management: 1.125 minutes per mark (75 min for 80 marks)
- Show all working: Even if final answer is wrong, method marks are available
- Units matter: Always include correct SI units with numerical answers
Paper 4 (Practical)
- Tables: Use headings with quantities AND units (e.g., "Length / cm")
- Graphs: Use more than half the grid paper, label axes, draw line of best fit
- Conclusion: Always relate your findings back to the original question
Paper 6 (Alternative to Practical)
- Describe, not explain: When asked to describe a method, give step-by-step instructions
- Safety: Always mention relevant safety precautions (e.g., wear goggles for radioactive sources)
- Variables: Clearly identify independent, dependent, and control variables
Mark Scheme Secret: Examiners use "marking points" - specific phrases they're looking for. Study past mark schemes to learn this exact wording. For example, for Newton's First Law, the mark scheme expects "constant velocity" not "same speed" (velocity includes direction).
Top 15 Common Mistakes to Avoid
- Confusing mass and weight: Weight = mass × g (weight is a force in Newtons)
- Wrong unit conversions: 1 km = 1000 m, 1 kW = 1000 W, 1 MJ = 1,000,000 J
- Forgetting direction in vector quantities: Velocity, force, momentum need direction
- Using diameter instead of radius: In circular motion and wave calculations
- Not reading question carefully: "Explain" needs reasoning, "state" just needs the fact
- Incomplete circuit diagrams: Must show complete loops and correct symbols
- Mixing up series and parallel rules: Current splits in parallel, voltage splits in series
- Ray diagrams without arrows: Rays must show direction of light travel
- Forgetting energy conservation: Total energy in = total energy out (may change forms)
- Wrong sign in temperature change: ΔT = final - initial (can be negative)
- Confusing speed of light in different media: Light slows down in denser materials
- Not simplifying fractions in lens equation: 1/f = 1/u + 1/v requires common denominator
- Forgetting to square in kinetic energy: KE = ½mv² (not ½mv)
- Missing units in graph axes: Automatic mark deduction in practical papers
- Using calculator in wrong mode: Check degrees vs radians for trigonometry
4-Week Practice Plan
Week 1: Mechanics & Forces
- Days 1-2: Motion, speed, velocity, acceleration calculations
- Days 3-4: Forces, Newton's laws, friction
- Days 5-6: Momentum and energy conservation
- Day 7: Past paper practice on mechanics topics
Week 2: Electricity & Thermal Physics
- Days 1-2: Circuit calculations, Ohm's law
- Days 3-4: Magnetism and electromagnetic induction
- Days 5-6: Heat transfer, specific heat capacity
- Day 7: Past paper practice on electricity and thermal topics
Week 3: Waves, Light & Nuclear
- Days 1-2: Wave properties, EM spectrum
- Days 3-4: Reflection, refraction, lenses
- Days 5-6: Atomic structure, radioactivity, half-life
- Day 7: Past paper practice on waves and nuclear topics
Week 4: Full Papers & Review
- Days 1-2: Complete Paper 2 (theory) under timed conditions
- Days 3-4: Complete Paper 4 or 6 (practical) under timed conditions
- Days 5-6: Review mistakes, focus on weak topics
- Day 7: Light revision, formula memorization, confidence building
Download the complete 4-week revision timetable (PDF) → Access Past Papers