What are good IB Physics IA ideas?

Good IB Physics IA ideas have a clear independent variable, accessible equipment, and a strong theoretical prediction to compare results against. Popular examples include investigating the coefficient of restitution of a tennis ball at different temperatures, the refractive index of sugar solutions, terminal velocity of coffee filters, and the effect of double glazing on heat loss. All 100 ideas on this page are organised by the themes of the current IB Physics syllabus (first examined 2025, and ongoing).

What is the IB Physics Internal Assessment?

In the current IB Physics syllabus the Internal Assessment is called the Scientific Investigation. It is an individual experimental report worth 20% of the final grade for both SL and HL students. Students design and carry out their own experiment, collect and analyse data, and write up their findings. Original ideas are not required by the IB.

How do I choose an IB Physics IA topic?

Choose an IB Physics IA topic by checking three things: can you clearly change one variable and measure another, can you access the equipment at school or at home, and does the investigation connect to real physics theory you can compare your results against. Avoid topics with too many uncontrolled variables. See the full list of 100 ideas on this page, organised by the themes of the current IB Physics syllabus.

Does the IB Physics IA need to be an original idea?

No. The IB has explicitly stated that original ideas are not required for the Physics Scientific Investigation. What matters is a clear research question, a well-designed experiment, and high-quality analysis. Using an established experimental setup with your own research question is perfectly acceptable.

What makes a high-scoring IB Physics IA?

A high-scoring IB Physics IA has a focused research question, a clean experimental design with controlled variables, sufficient data with proper uncertainty analysis, and a conclusion that engages directly with the underlying theory. The analysis section is where most marks are won or lost.

100 IB Physics IA Ideas [Updated 2026]

First, take a breath.

I’ve been teaching IB Physics since 2004, and every single year, without fail, I watch students completely freeze at this moment. The Scientific Investigation feels enormous. You’re supposed to come up with an original research question, design an experiment, collect data, analyse it, and write it up (all while also keeping up with the rest of your IB subjects).

Honestly, it’s a lot.

But here’s what I want you to know: you do not need to reinvent physics.

The IB examiners have explicitly said that original ideas are not required. You just need a clear, measurable research question, a well-designed experiment, and good analysis. That’s it.

So stop staring at a blank page and use this list. I’ve pulled together 100 ideas and organised them by the new 2025 syllabus themes so you can scroll straight to the physics you find most interesting. I’ve also starred a few favourites (ideas that students tend to love because they’re practical, produce clean data, and make for really satisfying write-ups).

Pick one. Get started. You’ve got this.

A quick note on what makes a good IA topic

Before you dive in, here are three things to check before you commit to an idea:

1. Can you clearly change one thing and measure another? A good IA has a clean independent variable (what you change) and a dependent variable (what you measure). If your experiment has too many variables you can’t control, your analysis will be a mess.

2. Can you actually get the equipment? Some ideas on this list need specialist kit. Most can be done with equipment available in a school lab or even at home. If in doubt, ask your teacher before you fall in love with an idea.

3. Does it connect to real physics? The best IAs have a clear theoretical prediction you can compare your results against. That’s what makes the analysis section sing and what earns you the top marks.

The 100 Ideas, Organised by Syllabus Theme

Theme A: Space, Time and Motion

(Covers kinematics, forces, momentum, energy, rigid body mechanics, and relativity)

How does the temperature of a tennis ball affect the coefficient of restitution? ⭐
How does the length of a bridge affect the sag when a constant mass is applied to the centre?
How does the breadth of a flat bridge affect the vertical depression when a known mass is added?
How does the mass of falling coffee filters affect their terminal velocity? ⭐
How does the mass of a toy parachute affect its terminal velocity?
How does the radius of a toy parachute affect its terminal velocity?
How does the angle of release of a golf club affect the distance travelled by the ball?
How does the angle of release of a single pendulum affect the deviation of time period from that predicted by simple pendulum theory?
How does temperature affect the spring constant of a spring?
How does temperature affect the range of flight of an elastic band?
How does temperature of a copper wire affect its Young Modulus?
How does the cross-sectional area of blades affect the lift force of a toy helicopter?
How does the angle of blade affect the lift force of a toy helicopter?
How does the number of blades affect the lift force of a toy helicopter?
How does the cross-sectional area of a football affect its terminal velocity?
How does the cross-sectional area of a sail on a toy boat affect the initial acceleration?
How does the radius of a football affect the impulse when kicked?
How does the mass added to an inflated balloon affect its terminal velocity?
How does the height of a ramp affect the time taken for a cylinder to roll down it?
How does the angle of a ramp affect the time taken for a block to reach the bottom?
How does the mass of a block affect its recoil distance after being impacted by a constant external force?
How does the temperature of rubber affect the coefficient of static friction between rubber and a surface? ⭐
How does the temperature of a lubricant affect the coefficient of dynamic friction when a solid is pulled along a surface?
How does the mass of a ball bearing affect the energy loss in a pendulum system when released from 90° and colliding with a wall?
How does the diameter of a ball in freefall affect the coefficient of restitution after one bounce on a hard surface?
How does the angle of initial release of a pendulum affect the subsequent calculation of g from the pendulum?
How does the rotational velocity of a basketball affect the horizontal travel distance when released in freefall? (Magnus Effect) ⭐
How does the pressure of a tyre affect the coefficient of dynamic friction?
How does the distance that an external force is applied to a cantilever affect the vertical depression?
How does the mass of a bullet in a ballistic pendulum affect the maximum height reached by the pendulum once the bullet has embedded?
How does the paddle area of a waterwheel affect the efficiency of the waterwheel when converting into electrical energy?
How does the temperature of grease affect the depth of crater created when a mass is dropped from a known height?

Theme B: The Particulate Nature of Matter

(Covers thermal energy, greenhouse effect, gas laws, and thermodynamics)

How does the distance between panes of glass in double glazing affect the rate of heat loss? ⭐
How does the number of panes of glass in double/triple/quadruple glazing affect the rate of heat loss?
How does a change in temperature of a copper rod affect its length of extension?
How does the concentration of salt in water affect the specific heat capacity?
How does the volume of water affect the rate of cooling when subjected to a controlled breeze?
Determine a numerical value for the gas constant. ⭐
How does the temperature of an ideal gas affect the average rate of wall collisions within a container? (good for simulation)

Theme C: Wave Behaviour

(Covers simple harmonic motion, wave model, wave phenomena, standing waves, resonance, and the Doppler effect)

How does light absorption through a glass plate change when more glass plates are added?
How does the thickness of SPF 30 sunscreen affect the intensity of UV light after penetrating through a constant-thickness plexiglass screen?
How does sugar concentration affect the refractive index of a sugar water solution? ⭐
Prove that the inverse square law holds for a point source light bulb but not for a directional light source.
How does temperature affect the speed of sound in a solid (or liquid)?
How does the length of a guitar string affect the sustain time when plucked with a constant force?
How does the temperature of a guitar string affect the frequency produced when plucked?
How does the diameter of a string affect the fundamental frequency?
How does the density of a string affect the fundamental frequency?
How does distance from a speaker affect the sound intensity level?
How does the slit spacing produced by a laser depend on the distance from the screen?
How does the density of a liquid affect the angle subtended by diffracted waves when the liquid passes through a single slit in a ripple tank?
How does the temperature of water in a wine glass affect the resonant frequency when the glass is struck? ⭐
How does the volume of water in a wine glass affect the resonant frequency when struck?
How does the cross-sectional area of card attached to a vibrating mass affect the displacement after twenty oscillations?
How does the diameter of a wire affect the damping constant of a pendulum?
How is the time period of oscillation of a solid sphere on a curved track affected by the radius of the sphere?
How does the slit width of a single slit affect the maximum angle of visible diffraction for a monochromatic source?
Does a pendulum obey the rules of SHM at large angles of release? ⭐
How does light intensity vary when passed through a polaroid filter at different angles?
How does the angle of incidence of p-polarised light affect its reflectivity?
Determine the width of human hair using single slit diffraction. ⭐
How does the refractive index of a material affect the intensity of light reflected from the boundary? (good for simulation)

Theme D: Fields

(Covers gravitational fields, electric and magnetic fields, and motion in electromagnetic fields)

How does the distance between two charged parallel plates affect the area of uniform electric field lines?
Use Coulomb’s Law to determine the number of excess electrons on a charged balloon.
Determine the mass of the electron experimentally using an electron deflection tube. ⭐
Determine the electric charge through the Millikan experiment.
How does temperature affect the magnetic field strength of a permanent magnet?
How does the magnetic field strength of a permanent magnet affect its levitation height above another permanent magnet?
Confirm the relative permeability of free space by varying the current of a solenoid and measuring the resulting magnetic field. ⭐
How does the magnetic field strength of bar magnets in a DC motor affect the angular velocity of the motor?
How does temperature affect the internal resistance of a battery? ⭐
How does the height of a water tube affect the power delivered by falling water in an electrical energy generator?
How does the diameter of the coil on a copper coil train affect the speed of the train?

Theme E: Nuclear and Quantum Physics

(Covers structure of the atom, quantum physics, radioactive decay, fission, and fusion)

Determine the spacing between atomic lattice planes in graphite using the de Broglie relationship. ⭐
Determine the work function of a given metal.
How does the voltage across a capacitor affect the energy stored?
Investigate the effect of connecting capacitors in series on the voltage across a discharging capacitor.
How does the temperature affect the efficiency of a diode bridge rectification circuit?

Practical Investigations (cross-theme)

These ideas draw on multiple areas of the syllabus and are particularly good for students who want a more open-ended investigation.

How does the volume of an object affect its buoyancy when fully submerged in water?
How does the volume of an object immersed in water affect buoyancy?
How does the mass of a body submerged in a fluid affect the volume displaced?
How does the density of an object fully immersed in water affect the time taken to reach equilibrium once released?
How does the cross-sectional area of the pipe in a siphon affect the volumetric flow rate?
How does the drop height of a water droplet affect the rebound height upon contact with a water surface?
How does temperature affect the viscosity of castor oil? ⭐
How does the moment of inertia affect the final velocity of a cylinder rolling down an inclined slope?
How is the e.m.f. induced in a coil affected by the height from which a magnet is dropped through it? ⭐
How does varying the frequency of rotation of a simple AC generator affect the induced peak e.m.f.?
How does the radius of a copper pipe affect the time taken for a magnet to drop through it?
How does the voltage applied to a Helmholtz coil affect the period of a pendulum oscillating freely within the loop?
How does the temperature affect the efficiency of a transformer?
How does the resistivity of a metal pipe affect the time taken for a magnet to drop through it?
How does the mass of a falling coffee filter stack affect the terminal velocity? (variation on #4, excellent for modelling drag)
How does the angle of a ramp affect the acceleration of a wheeled trolley down it?
How does the thickness of cellophane covering a solar panel affect the efficiency of the panel?
How does the frequency of electromagnetic radiation (in the visible spectrum) affect the output energy from a solar panel?
How does temperature affect the output voltage of photovoltaic cells? ⭐
How does the concentration of a solution affect the angle of rotation of polarised light? (optical activity)
How does the diameter of a cannonball affect the time taken to reach the ground, assuming a constant drag coefficient? (good for simulation)
How does the mass of a toy parachute payload affect the descent rate? (variation of #5, excellent for real-world data)

⭐ = Sally’s picks. These tend to produce clean data, have clear theoretical backing, and make for really satisfying write-ups.

You’ve got your idea. Now what?

Here’s the honest truth: most students don’t lose marks in the IA because they chose the wrong topic. They lose marks because they don’t understand what the examiner is actually looking for.

The IA marking criteria rewards specific things. You need to know how to structure your analysis, what level of uncertainty treatment is expected, and how to write a conclusion that actually engages with the theory. That’s all teachable, and it’s exactly the kind of thing I break down in the GradePod Exam Pack.

The Exam Pack isn’t just about the written exams. It gives you the frameworks and question practice to understand IB Physics at the level where everything clicks: the concepts, the exam technique, and the way the IB actually thinks about your work.

If you’re at the stage where you’re researching IA ideas, you’re probably in DP1 or early DP2. That means your exams are closer than they feel. Now is exactly the right time to build the foundations.

Get the GradePod Exam Pack for £39 →

Everything you need. One price. No subscription. I promise it works.

Sally Weatherly is the founder of GradePod, a Fellow of the Institute of Physics, and the author of four IB Physics books (two of which hit #1 on the Amazon bestseller list). She has been teaching IB Physics since 2004 and has helped 30,000+ students since launching GradePod in 2020.