What is the easiest IB Physics IA topic?

There is no single easiest topic because feasibility depends on your equipment and measurement skills. Pendulums, cooling curves, resistance against wire length, and resonance in air columns are usually accessible in school laboratories. Their advantage is that each has a clear theoretical model and requires relatively simple apparatus. However, a familiar experiment still needs a focused question, repeated measurements, uncertainty treatment, and thoughtful evaluation. Choose the setup that gives you the most consistent pilot data rather than the one with the shortest equipment list.

Does an IB Physics IA topic have to be original?

The topic does not need to investigate a phenomenon that nobody has studied before. What matters is that you formulate and investigate your own focused research question, generate appropriate data, and make your own analytical decisions. You can personalize a familiar setup through the selected variable, measurement method, range, model comparison, or physical context. Artificially adding complexity often produces more uncontrolled variables without improving the investigation. Never copy another student's data, wording, processing, or method as if it were your own.

How many data points should a Physics IA have?

The IB does not prescribe one universal number of data points or repetitions for every Physics investigation. As practical guidance, many continuous-variable experiments benefit from at least 5 distinct values spread across a meaningful range and repeated trials at each value. The appropriate amount depends on variability, measurement precision, available time, and the model being tested. More measurements do not repair a poorly controlled method or an independent-variable range that is too narrow. Use a pilot study to decide whether your dataset will reveal a trend and support uncertainty-based conclusions.

Can I use a phone for my IB Physics IA?

A phone can be useful for video analysis, timing, frequency measurement, light readings, or sound recording. You must still explain how the measurement is obtained and consider the application's resolution, sampling rate, calibration, and limitations. Keep the phone position fixed and include a reference scale when analysing motion from video. Uncalibrated sensor output may be suitable for relative comparisons but should not automatically be treated as an accurate absolute measurement. Confirm your proposed application and data-collection method with your teacher before relying on it.

Are simulations allowed for an IB Physics IA?

The scientific investigation can involve approaches other than a conventional bench experiment, subject to the current guide and your teacher's approval. A simulation-based investigation must still address a focused question and support meaningful analysis rather than merely reproduce a known graph. You should explain the model, identify assumptions, vary parameters systematically, and evaluate how the simulation differs from a physical system. A black-box simulator is risky if you cannot explain how its outputs are generated. For most students, a simple experiment with primary measurements is easier to justify and evaluate convincingly.

Can SL and HL students use the same Physics IA topics?

SL and HL students complete the same type of scientific investigation and are assessed using common criteria. An HL student is not automatically required to select more expensive equipment or an obscure university-level topic. The physics should be understood accurately and should provide enough depth for appropriate modelling and interpretation. A simple topic can support sophisticated analysis through linearisation, parameter estimation, uncertainty propagation, residuals, or comparison of competing models. Select a question that you can explain confidently rather than one that merely sounds advanced.

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IB Physics IA Topics That Actually Work

IB Physics Internal Assessment IB IA

• 28 Sept 2026•11

Join 650k+ students breezing through the IBReady to breeze through the IB?

IB Physics IA Topics That Actually Work | RevisionDojo

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IB Physics IA Topics That Actually Work

IB Physics Internal Assessment IB IA

• 28 Sept 2026•11

The best IB Physics IA topics are focused questions that produce repeatable measurements, connect to a clear physical model, and allow meaningful uncertainty analysis, conclusion, and evaluation. They do not need to be technologically advanced or completely original.

This guide presents low-equipment Physics IA ideas for a typical school laboratory. It also explains how to test an idea, formulate a research question, and reject an unsuitable experiment before it consumes your available time.

What the current IB Physics IA requires

The Physics IA is officially called the scientific investigation. Under the course first assessed in 2025, it is worth 20% of the final Physics grade at both SL and HL, has an allocated duration of 10 hours, and produces an individual report with a maximum of 3,000 words.

Assessment uses four equally weighted criteria:

Criterion	Maximum marks	Central concern
Research design	6	Does the method generate data relevant to a focused question?
Data analysis	6	Is the data processed and interpreted appropriately?
Conclusion	6	Does the conclusion answer the question using data and physics?
Evaluation	6	Are limitations explained and realistic improvements proposed?

Because conclusion and evaluation together account for half of the available marks, a simple experiment with a testable model can be more effective than an ambitious setup producing unreliable data. The official IB Physics subject brief summarizes the assessment, while the IB Physics curriculum update explains the revised investigation.

What makes an IB Physics IA topic workable?

A promising topic should have:

One measurable independent variable, preferably numerical and continuous
One clearly defined dependent variable that can be measured repeatedly
A theoretical relationship predicting a trend, gradient, intercept, or constant
Controllable conditions, such as temperature, material, position, or ambient light
Enough analytical depth for graphing, uncertainties, model comparison, and evaluation

“Investigating pendulums” is only a subject area. A better question is: “How does pendulum length affect the square of the period for oscillations released from a constant angle of 8°?” It gives the predicted relationship

T^2=\frac{4\pi^2}{g}L.

Changing length, mass, amplitude, and bob shape simultaneously would make the results difficult to interpret. Begin with one independent variable and introduce another condition only when it supports a purposeful comparison.

Low-equipment IB Physics IA topic ideas

Treat these questions as adaptable starting points, not titles to copy unchanged.

Mechanics and oscillations

Motion can often be measured with a phone camera, ruler, stopwatch, balance, or ramp.

How does inclined-plane angle affect a trolley's acceleration?
How does sandpaper grit number affect the critical sliding angle of a block?
How does ball pressure affect coefficient of restitution?
How does pendulum release angle affect period beyond the small-angle approximation?
How does cantilever length affect fundamental frequency?

For a bouncing ball, video analysis can determine

e=\sqrt{\frac{h_2}{h_1}},

where $h_1$ and $h_2$ are the release and rebound heights. Control the surface, camera position, release method, and ball temperature.

Waves and sound

Wave investigations can provide many measurements without specialized sensors, although phone applications should be checked for resolution and consistency.

How does air-column length affect the resonant frequency of a closed tube?
How does string tension affect fundamental frequency?
How does material thickness affect relative sound attenuation?
How does cantilever length affect its resonant frequency?

For a stretched string,

f=\frac{1}{2L}\sqrt{\frac{F}{\mu}}.

Varying tension $F$ and graphing $f$ against $\sqrt{F}$ allows the gradient to estimate linear density $\mu$ . Limitations could include pulley friction, non-uniform density, and uncertainty in vibrating length.

Thermal physics

Thermal investigations usually need only containers, water, insulation, and temperature probes.

How does insulation thickness affect the cooling constant of water?
How does exposed surface area affect cooling rate?
How does initial temperature difference affect Newton's law of cooling?
How does airflow speed affect the cooling constant?

For Newton's law of cooling,

T-T_a=(T_0-T_a)e^{-kt}.

A graph of $\ln(T-T_a)$ against time should have gradient (-k). This offers more analytical depth than simply identifying which container cools fastest. Monitor room temperature, evaporation, probe position, and container geometry.

Electricity, magnetism, and optics

Keep electrical supplies at safe low voltages and prevent components from overheating. Follow school laser-safety rules during optics work.

How does wire length affect resistance for a fixed material and diameter?
How does temperature affect the resistance of a thermistor?
How does coil separation affect induced voltage?
How does distance from a lamp affect illuminance?
How does solar-cell angle affect electrical power?
How does solution concentration affect refractive index?

Rather than merely confirming $V=IR$ , estimate resistivity from the gradient of resistance against wire length. Discuss contact resistance and wire-diameter uncertainty. An illuminance investigation can test an inverse-square model if background light is controlled and the detector is not saturated.

Fluids

How does liquid temperature affect a sphere's terminal velocity in glycerine?
How does fluid depth affect outflow speed from an opening?
How does submerged volume affect buoyant force?
How does tube radius affect flow rate under a fixed pressure head?

Terminal-velocity experiments require a sufficiently tall container and a region where the object has stopped accelerating. Confirm this with a pilot video before collecting the full dataset. Further starting points appear in RevisionDojo's fresh Physics IA ideas and unusual Physics IA ideas.

How to choose between Physics IA ideas

Conduct a short pilot at the lowest, middle, and highest planned values of the independent variable. If the dependent variable changes by less than its measurement uncertainty, widen the range, improve the instrument, or reject the topic.

Score each candidate from 1 to 5:

Test	What to check
Feasibility	Can the setup be assembled and tested quickly?
Signal size	Is the observed change larger than measurement uncertainty?
Repeatability	Are repeated measurements reasonably consistent?
Physics depth	Can you test or transform a meaningful model?
Control	Can major external variables be controlled or monitored?
Safety	Does the procedure comply with school rules?

Plan the analysis before collecting all data. Decide which graph you expect, whether linearisation is justified, what its gradient represents, and how uncertainties will be treated. RevisionDojo's IB Physics Study Notes can clarify the model, while the Physics Questionbank can reveal gaps in your understanding.

Designing data collection and uncertainty analysis

A workable topic must also support enough data for credible uncertainty treatment. Record instrument resolution or manufacturer uncertainty before collection, and distinguish uncertainty from the spread in repeated readings. For each independent-variable value, take enough repeats to calculate a mean and describe random variation; repeating a measurement without resetting the apparatus may underestimate that variation.

Use error bars when they help show measurement uncertainty, but do not assume every uncertainty is a fixed percentage. Timing uncertainty, length resolution, sensor calibration, and video frame rate enter calculations differently. If a derived quantity is calculated, propagate the relevant input uncertainties using a method appropriate to the course and explain it consistently.

Also check for systematic effects. A zero offset, parallax, heat loss to the container, or friction can shift every result in the same direction and will not disappear through repetition. Compare the fitted gradient or constant with the theoretical value using percentage difference and combined uncertainty where justified. Residual plots can reveal curvature or changing scatter that a single correlation coefficient may hide. This planning makes the eventual conclusion quantitative and gives the evaluation specific evidence rather than generic comments.

Common topic-selection mistakes

Choosing a category instead of variables: “Thermal conductivity” does not identify what changes or what is measured.
Using only categorical comparisons: Numerical variables such as thickness, area, or temperature usually permit stronger modelling than comparing named materials.
Relying on untested equipment: Verify the range, resolution, sampling rate, and consistency of sensors and applications.
Adding complexity to appear original: Originality cannot compensate for uncontrolled variables or poor measurements.
Ignoring safety: Avoid mains electricity, uncontrolled projectiles, high-power lasers, dangerous heating, and improvised radiation experiments.
Copying an exemplar: Use Physics IA examples to study structure, not to reproduce another student's work.

From topic to research question

A useful structure is:

How does [independent variable with range and unit] affect [measured dependent variable] in [defined physical system], under [important controlled conditions]?

The question should make the investigated relationship unambiguous without becoming unreadable. The IB Physics IA planning tips and current rubric explanation provide useful checks once you have a candidate.

Conclusion

Effective IB Physics IA topics combine measurable variables, accessible equipment, a defensible model, and repeatable data. Run a pilot, reject effects smaller than your measurement uncertainty, and prioritize analytical quality over novelty.

RevisionDojo's IB Physics IA Grader, exemplars, Study Notes, and Jojo AI can help identify weaknesses while leaving the scientific decisions and final writing to you.

Sources and referenced URLs

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