The IB Physics Internal Assessment (IA) carries 20% of your final mark in IB DP Physics — making it the highest-leverage single piece of work in the qualification. A strong IA can lift your overall grade by half a band; a weak one can prevent a grade 7 even with strong written-paper performance.

This guide goes deeper than our overview of IB IA topic ideas across all subjects to focus specifically on Physics: 25 topic ideas with research questions, the criteria broken down with what each one rewards, common pitfalls and what a high-scoring Physics IA looks like.

Free resource: Use Tutopiya’s IB DP Physics revision checklist to confirm your topic choice connects to a syllabus area you understand at depth.

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How the IB Physics IA is marked

The Physics IA is assessed against five criteria for a total of 24 marks:

Criterion	Marks	What it rewards
Personal engagement	2	Genuine curiosity, original thinking
Exploration	6	Focused research question, methodology, controlled variables
Analysis	6	Data treatment, uncertainty propagation, graph analysis
Evaluation	6	Conclusions linked to data, limitations, suggested improvements
Communication	4	Logical structure, clarity, scientific language and citations

A grade 7 Physics IA typically sits at 20–22/24. Physics IAs are notably hard to top because the demand for uncertainty propagation through equations and graphical analysis is more rigorous than in Biology.

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The five criteria, broken down

Personal engagement (2 marks)

A genuine reason for the topic, an original design choice, your voice in the write-up.

Exploration (6 marks)

Examiners want:

• A focused research question with named physical quantities, named technique and quantifiable variables.
• Background physics including the relevant equations and what each variable represents.
• Methodological rationale — why this technique over alternatives.
• Controlled variables with explicit control method.
• Risk assessment — important for electrical, optical and high-temperature setups.

A research question like “How does mass affect a pendulum?” will lose 4 of 6 marks. “How does the length L (m) of a simple pendulum affect its period T (s) at small angles, and does the relationship match T = 2π√(L/g)?” will earn most of the 6.

Analysis (6 marks)

Physics-specific demands:

• Raw data tables with units and uncertainties for every measured quantity.
• Uncertainty propagation through any calculated quantity — relative uncertainties for products, absolute uncertainties for sums.
• Graphical analysis with error bars — slope and intercept extracted, often with a linearised form (e.g. T² vs L for pendulum).
• Comparison to expected value where physics theory predicts one.

Physics IAs that miss the linearisation step (e.g., plotting T vs L instead of T² vs L) frequently lose 2–3 marks.

Evaluation (6 marks)

Examiners want a quantitative conclusion, realistic limitations discussed numerically, and specific improvements. The most-missed mark is the third — improvements that are vague (“use a stopwatch with better precision”) earn less than improvements that are quantified (“replace human-reaction stopwatch (±0.2 s) with photogate (±0.001 s), reducing 8% timing uncertainty to 0.04% over a 0.5 s period”).

Communication (4 marks)

Standard sections, 6–12 pages, full citations, SI units, equations rendered correctly.

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25 IB Physics IA topic ideas with research questions

These are deeper and more specific than the 10 in our overview article.

Mechanics

1. Pendulum — How does length L (m) affect the period T (s) of a simple pendulum, and does T² ∝ L?
2. Spring constant — How does mass affect the period of a spring oscillator, and does the data fit T = 2π√(m/k)?
3. Projectile range — How does launch angle affect projectile range from a spring-loaded launcher at fixed initial speed?
4. Friction coefficient — Determining the coefficient of static friction between rubber and wood by measuring tilt angle.
5. Terminal velocity — How does mass (number of stacked coffee filters) affect terminal velocity in air?

Waves and oscillation

6. String tension and frequency — How does string tension affect the fundamental frequency of a vibrating string?
7. Speed of sound — Determining the speed of sound in air using a resonating tube.
8. Refractive index — Determining the refractive index of glass using Snell’s Law.
9. Diffraction — How does slit width affect the angular position of single-slit diffraction minima?
10. Standing waves — How does the length of a Chladni plate affect resonant mode frequencies?

Electricity and magnetism

11. Resistivity — How does the diameter of a wire affect its electrical resistance, and does R ∝ 1/A?
12. Internal resistance — Determining the internal resistance of a battery using terminal voltage versus current.
13. Capacitor discharge — How does the capacitance C affect the time constant τ = RC of an RC discharge circuit?
14. Electromagnetic induction — How does the rate of change of flux affect the EMF induced in a coil?
15. Solar cell efficiency — How does light angle affect the power output of a photovoltaic cell?

Thermal physics

16. Specific heat capacity — Determining the specific heat capacity of aluminium using an electrical heater and calorimeter.
17. Cooling rate — How does surface area affect the cooling rate of a hot water beaker (Newton’s law of cooling)?
18. Latent heat — Determining the latent heat of fusion of ice using mixing calorimetry.

Modern physics

19. Inverse square law — Does the intensity of a point light source fall as 1/r² as predicted by the inverse square law?
20. Photoelectric threshold — Determining the threshold frequency for the photoelectric effect using LEDs of different wavelengths.
21. Half-life simulation — Modelling radioactive decay using dice — does the data fit an exponential decay?

Applied physics

22. Bottle whistle — How does the volume of liquid in a bottle affect the resonant frequency when blown across the top (Helmholtz resonator)?
23. Pinhole camera — How does pinhole diameter affect image sharpness in a pinhole camera?
24. Heat insulation — How does insulation thickness affect heat loss through a calorimeter wall?
25. Capacitor circuit time constant — How does the resistance R affect the time constant of an RC circuit measured by oscilloscope?

For broader topic ideas across the IB sciences, see our overview of IA topic ideas by subject.

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What a high-scoring Physics IA looks like

A 21/24 Physics IA shares six common features:

1. A specific, measurable, physically meaningful research question with named quantities and units.
2. A method that controls 4–6 variables explicitly.
3. At least 6 levels of the independent variable, each repeated 3–5 times.
4. Uncertainty propagation through every calculated quantity.
5. A linearised graph with error bars, slope and intercept extracted, with a clear physical interpretation.
6. A comparison to a theoretical or literature value with percentage error discussed.

Length: typically 9–11 pages.

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Common Physics IA pitfalls

Five errors come up consistently:

1. No linearisation. Plotting T vs L for a pendulum (curve) instead of T² vs L (line) costs 2–3 marks in Analysis.
2. No uncertainty propagation. Stating uncertainties on raw measurements without propagating them costs 2–3 marks.
3. Insufficient repeats. Three repeats per IV level minimum; five is better.
4. Vague evaluation. “There were random errors” loses marks where “The stopwatch had ±0.2 s uncertainty contributing 8% to a 2.5 s period; using a photogate would reduce this to <0.1%” gains them.
5. Missing background equations. Quoting “there is a relationship” without the predicted equation costs Exploration marks.

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How to plan your Physics IA timeline

A useful Physics IA timeline runs over 3–4 months:

• Month 1: Topic selection, literature review, draft research question.
• Month 2: Method finalisation, pilot, full data collection.
• Month 3: Analysis with uncertainty propagation, draft write-up.
• Month 4: Final revisions, teacher feedback, submission.

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Frequently asked questions

How long should an IB Physics IA be?

The IB recommends 6–12 pages of content. Most high-scoring IAs sit at 9–11 pages.

Do I need to linearise my data?

Where the underlying physics relationship is non-linear (e.g., T = 2π√(L/g)), a linearised graph (T² vs L) is expected. The slope of the linearised graph then has a clear physical interpretation.

What’s the difference between random and systematic uncertainty?

Random uncertainties cause spread in repeated measurements; reducing them requires more repeats or better instrumentation. Systematic uncertainties shift all values consistently; reducing them requires calibration or method change. Discuss both in Evaluation.

Should I include a comparison to a theoretical value?

Yes, where physics theory predicts one. For a pendulum, g should come out at ~9.81 m s⁻². Quote your value, the theoretical value, and the percentage error.

Can I use sensors and software for data collection?

Yes — photogates, force sensors, voltage probes are all routinely used in IB Physics IAs and reward better Analysis marks because the uncertainty is lower than human-eye/stopwatch combinations.

How does the IA mark connect to my final IB Physics grade?

The IA contributes 20% of your subject grade. See our IB DP Physics grade boundaries guide for how the IA mark is combined with Paper 1 and Paper 2 to award a 1–7 grade.

Does the IA topic have to relate to the syllabus?

The topic must be in the scope of IB Physics but does not need to be directly from a syllabus topic. It can extend a syllabus area.

What’s the most common reason Physics IAs lose Exploration marks?

Missing background equations and missing methodological reasoning. “I will time the pendulum” is method; “I will time 10 oscillations and divide by 10 to reduce reaction-time uncertainty by a factor of ten” is method with reasoning.

Can my IA fail to confirm the theoretical relationship?

Yes — and that’s fine if the analysis is rigorous. A graph that doesn’t fit theory is still a valid result if your uncertainties don’t fully overlap with theory. Strong evaluation of the discrepancy can score full marks.

How many hours should I spend on the IA?

The IB allocates 10 hours of class time plus your independent work. High-scoring IAs typically involve 30–50 hours total.

Should I use a computer simulation instead of physical equipment?

Computer-based “experiments” can score IAs but typically lose marks in Personal Engagement and Exploration unless you justify the simulation choice and discuss its limitations.

What’s the most common Communication mistake in Physics IAs?

Equations that don’t render correctly, missing units in graphs and tables, and inconsistent significant figures. Always proofread for these before submission.

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Last reviewed: 29 April 2026. The IB Physics IA is moderated against published criteria. Always work from the official IB Physics subject guide and your teacher’s feedback. For broader subject-IA ideas, see our IB IA topic ideas by subject overview.

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