IB Physics Extended Essay: Research Questions, Method and Analysis
A Physics EE investigates one focused, testable relationship using experiment, data or simulation. Here is how to design it, deal with uncertainty and write it up.
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Published October 2026·Written by Ahmed Raees, Founder·Reviewed by experienced IB Diploma tutors
Quick answer: An IB Physics Extended Essay is a 4,000-word investigation of a focused, testable physics question, usually answered through your own experiment, a published dataset or a simulation, analysed with physics theory. From May 2027 it is marked out of 30, and Discussion and evaluation (8 marks) is where uncertainties, limitations and alternative explanations are judged.
This guide is the Physics companion to our main IB Extended Essay guide. It covers how to choose a question you can genuinely investigate, the main types of method, how to handle data and uncertainty, and what the 2027 criteria mean for a physics write-up. It assumes you are taking IB Physics, though the essay can go beyond the syllabus.
What makes a good Physics EE research question?
A Physics research question should define one independent variable, one dependent variable and the system you are studying, and it should be grounded in a physical model you can test. "How does a guitar work?" is a topic. "How does the tension in a nylon string affect the frequency of its fundamental mode, and how well does the model for a stretched string predict it?" is a question you can measure, analyse and evaluate.
Clear variables and controls, with a realistic range of values.
A theory to test: an equation or model that predicts the relationship, so your analysis has something to compare against.
Feasible equipment and time: school lab apparatus, a phone sensor, a simple rig at home, a public dataset or simulation software.
Depth beyond a standard practical: a twist, extension or real-world application that turns a class experiment into research.
Example Physics EE research questions
Original examples to illustrate the format; your own question should come from something you find puzzling.
How does the temperature of a rubber ball affect its coefficient of restitution when dropped onto a steel plate?
How does the length of a magnet falling through a copper tube affect its terminal velocity, and how well does a simple eddy-current model fit?
How does the concentration of a sugar solution affect its refractive index, measured with a laser and a semicircular tank?
How does the angle of a solar panel relative to a lamp affect its power output, compared with the cosine model?
How does the mass of water in a glass affect the frequency of the tone produced when its rim is rubbed?
Using published data, how closely do the orbital periods of one planet's moons follow Kepler's third law?
Choosing a method: experiment, data or simulation
Your own experiment: the most common route. Plan enough data points across a wide range, repeat readings, and record uncertainties from the start.
Secondary data: astronomical, climate or particle data from reputable public databases can support excellent essays if you do real analysis on them.
Simulation or modelling: numerical models or simulation software, ideally checked against real data or theory.
Whatever the route, discuss safety and feasibility with your supervisor early. A simple, well-controlled method analysed carefully is better than an ambitious set-up that never produces reliable results.
IB Physics Extended Essay structure
Introduction: the research question, the context and why it is interesting.
Background theory: the physics behind the question and the model or equation your results will test.
Method: variables, controls, apparatus, procedure and how uncertainties were estimated, with a diagram or photo of the set-up.
Results: processed data in clear tables and graphs, with units, uncertainties and error bars; raw data can go in an appendix.
Analysis: lines or curves of best fit, gradients and intercepts interpreted physically, and comparison with the theoretical prediction.
Evaluation and conclusion: how far the data support the model, the main sources of error, limitations and improvements, and a clear answer to the question.
How the 2027 criteria apply to Physics
Criterion (marks)
What it looks like in Physics
A: Framework for the essay (6)
A focused, testable question, a method matched to it and a logical write-up with clear headings, labelled graphs and references.
B: Knowledge and understanding (6)
Correct physics, units and terminology, and a model explained well enough to be tested.
C: Analysis and line of argument (6)
Data processing and graphs that build towards an answer, with each result interpreted physically.
D: Discussion and evaluation (8)
Treatment of uncertainties, systematic errors, the validity of the model and alternative explanations, leading to a justified conclusion.
E: Reflection (4)
Your reflection on decisions you made during the investigation and what you learned from problems along the way.
The Discussion and evaluation criterion rewards students who go beyond "human error". Quantify uncertainties where you can, explain which errors are random and which are systematic, and say how they affect the conclusion.
Data, uncertainties and graphs
Range and repeats: aim for enough independent-variable values to show the shape of the relationship, with repeats to estimate random uncertainty.
Linearise where possible: rearranging the model into a straight-line form makes the gradient meaningful and the comparison with theory clearer.
Error bars and best-fit lines show the reliability of your result at a glance.
Percentage difference from the theoretical value, discussed alongside the uncertainty, helps you judge the model honestly.
Physics essays can lose words to long method descriptions. Use a clear diagram and a concise numbered procedure, put raw data in an appendix, and keep the words for theory, analysis and evaluation. Content beyond 4,000 words is not assessed. Equations, tables and graph labels are part of how physics is communicated, so keep them precise.
Common Physics EE mistakes
A repeated class practical with no extension or deeper question.
Too few data points or too narrow a range to test the model.
Uncertainties ignored or handled only in the final paragraph.
No theoretical prediction, so the results cannot be judged against anything.
Graphs without units, error bars or proper labels.
Vague evaluation such as "the experiment could be more accurate" without saying how or why.
A Physics EE timeline
Early DP1: note physics questions you would like answered and check what equipment or data you could use.
Mid DP1: run a quick pilot to test the method before agreeing the question at your first reflection session.
Summer or early DP2: collect the main data while there is lab access and time to repeat readings.
Early DP2: process the data, write a full draft and review it at the second reflection session.
Final weeks: strengthen the evaluation and uncertainties, check references and complete the final reflection session (viva voce).
Supervision is recommended at three to five hours including three mandatory reflection sessions. Your Physics internal assessment uses similar skills, so planning both together saves time.
Want feedback on your Extended Essay plan?
Our 1-on-1 IB tutors help students sharpen a research question, plan the structure and understand the criteria. The essay must be your own work: we coach the skills, we do not write it. Free diagnostic consultation.
Many physics questions connect to chemistry, engineering or environmental science. If the question is answered with physics theory and data, keep it subject-focused. If it truly needs another discipline as an equal part, read the interdisciplinary guidance with your supervisor; compare how evidence works in our Economics EE guide or a Chemistry-focused approach.
A good Physics question names one independent and one dependent variable in a specific system, and can be compared with a physical model, for example how string tension affects frequency. It should be feasible with the equipment, data or software you can access.
No. Most Physics essays use the student's own experiment, but strong essays can also be based on published datasets or simulations, provided you do genuine analysis and evaluation of the data.
Record uncertainties from the start, use repeats to estimate random error, show error bars on graphs, and discuss which errors are random and which are systematic and how they affect your conclusion.
From May 2027 it is marked out of 30 on five criteria: Framework for the essay (6), Knowledge and understanding (6), Analysis and line of argument (6), Discussion and evaluation (8) and Reflection (4). The total converts to a grade from A to E.
Only as a starting point. Extend it with a deeper question, a wider range, a new variable or a real-world application, so the essay is an investigation rather than a repeat of a standard practical.
