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Physics Extended Essay Guide
A guide to designing a quantitative, theory-grounded IB Physics Extended Essay with rigorous data analysis.
What is a Physics Extended Essay?
The Physics Extended Essay (EE) is one of the most challenging and rewarding parts of the IB Diploma. Below you will find everything you need to choose a strong topic, design your methodology, and write a high-scoring EE in Physics.
Word Count
3,500 – 4,000 words
Excluding bibliography, abstract, and appendices. Budget every section carefully before you start writing.
Assessment
Graded A–E
Combined with the TOK essay for up to 3 bonus IB Diploma points. A strong EE and TOK = maximum bonus.
Timeline
12–18 months
From initial topic to final submission. Most students underestimate this. Start early and plan backwards from your deadline.
Supervision
3 required meetings
Initial, interim, and final (viva voce). Each requires an RPPF reflection. Your supervisor approves your RQ.
Strong Physics EE Topic Ideas
| Topic Idea | Why It Works | Difficulty |
|---|---|---|
| How does the length of a pendulum affect its period, and to what extent does the small-angle approximation hold? | Classical mechanics, measurable, theory-testing | Easy |
| How does temperature affect the resistivity of a semiconducting material? | Solid state physics, measurable, theory-rich | Medium |
| To what extent does the Magnus effect explain the trajectory of a spinning football? | Fluid dynamics, projectile motion, interesting | Medium |
| How does the angle of incidence affect the reflectivity of a dielectric surface? Testing Fresnel’s equations | Optics, Fresnel equations, measurable | Hard |
| How does magnetic field strength affect the Hall voltage in a semiconductor? | Electromagnetism, Hall effect, quantitative | Hard |
| To what extent does the diffraction pattern of a single slit conform to Fraunhofer theory? | Wave optics, quantitative, laser safety considerations | Medium |
Subject-Specific Advice
Linearity
Plot and linearise your graphs
Physics EEs score highly when students linearise their data (e.g. plot T² vs L for a pendulum) and find the gradient to calculate a physical constant. This shows deep physical understanding.
Uncertainty
Propagate all uncertainties
Report every measurement with uncertainty. Propagate uncertainties through derived quantities. Plot error bars on all graphs. Compare your experimental value with the theoretical value within uncertainty bounds.
Physical Theory
Connect results to equations
Derive the relevant equation from first principles if possible. Show how your experimental results confirm, modify, or deviate from the theoretical prediction.
Safety
Lasers, high voltage, radioactivity
Some Physics EEs involve lasers or high-voltage equipment. Complete a risk assessment with your teacher before starting. Never work alone with hazardous equipment.
Assessment & Common Mistakes
Assessed on: physics knowledge, experimental design, data analysis (including uncertainties and graphical work), and critical evaluation. Physics EEs are expected to apply physical theory rigorously and compare experimental results to theoretical predictions.
⚠ Common Pitfall
Students collect data but fail to connect it to physical theory. A Physics EE that just says “my results show T increases with L” without deriving the pendulum equation, comparing experimental to theoretical period, and discussing sources of systematic error is missing the essential physics.
Physics EE Checklist
- ✓ My RQ asks a specific quantitative physics question — with measurable variables
- ✓ All measurements have absolute and percentage uncertainties
- ✓ I have linearised my data to extract a physical constant or test a physical relationship
- ✓ Error bars are plotted on all graphs
- ✓ My discussion compares my experimental value with the theoretical value
- ✓ I explain the physical mechanism behind any deviation from theory
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