The IB Physics syllabus, theme by theme

By The STEM-Tutor team · Updated October 2026

IB Physics was rebuilt for first assessment in 2025. The old numbered topics and options are gone; instead there are five themes, A to E, studied by every student, with extra depth at HL. Here is the whole course in one place, and how it is examined.

The course at a glance

The current IB Physics guide was first assessed in May 2025. Every student studies the same five themes. Standard level (SL) is planned for 150 teaching hours and higher level (HL) for 240. HL students meet extra topics and go deeper in the shared ones, but there are no longer any options to choose between.

• A. Space, time and motion: about 27 hours at SL and 42 at HL.
• B. The particulate nature of matter: about 24 hours at SL and 32 at HL.
• C. Wave behaviour: about 17 hours at SL and 29 at HL.
• D. Fields: about 19 hours at SL and 38 at HL.
• E. Nuclear and quantum physics: about 23 hours at SL and 39 at HL.

On top of the content, the guide sets aside time for the experimental programme: practical work through the course, the collaborative sciences project, and 10 hours for the scientific investigation that becomes your internal assessment (IA).

Theme A: Space, time and motion

This is classical mechanics, the foundation for everything else.

• A.1 Kinematics: displacement, velocity and acceleration, the equations of motion for constant acceleration, motion graphs and projectiles.
• A.2 Forces and momentum: Newton's laws, free-body diagrams, friction, momentum, impulse and collisions, and circular motion.
• A.3 Work, energy and power: work done by a force, kinetic and potential energy, conservation of energy, power and efficiency.
• A.4 Rigid body mechanics (HL only): torque, moment of inertia, angular momentum and rotational kinetic energy.
• A.5 Galilean and special relativity (HL only): reference frames, the postulates of special relativity, time dilation, length contraction and spacetime diagrams.

Theme B: The particulate nature of matter

• B.1 Thermal energy transfers: temperature, internal energy, specific heat capacity, specific latent heat, conduction, convection and radiation, including black-body radiation.
• B.2 Greenhouse effect: energy balance of the Earth, albedo and emissivity, and why greenhouse gases warm the surface.
• B.3 Gas laws: pressure, the ideal gas law and the kinetic model of an ideal gas.
• B.4 Thermodynamics (HL only): the first and second laws, entropy, and heat engines.
• B.5 Current and circuits: charge, current, potential difference, resistance and resistivity, power, series and parallel circuits, and internal resistance.

Putting circuits in Theme B surprises students who learned them as “electricity”. The logic is that current is the movement of charged particles through matter.

Theme C: Wave behaviour

• C.1 Simple harmonic motion: the defining condition a = −ω²x, period and frequency, and energy in oscillations, with more of the mathematics at HL.
• C.2 Wave model: transverse and longitudinal waves, wave speed, frequency and wavelength, and the electromagnetic spectrum.
• C.3 Wave phenomena: reflection, refraction and Snell's law, diffraction, interference, and the double-slit experiment.
• C.4 Standing waves and resonance: nodes and antinodes, harmonics on strings and in pipes, and damping.
• C.5 Doppler effect: the change in observed frequency for moving sources or observers, including light from moving galaxies.

Theme D: Fields

• D.1 Gravitational fields: Newton's law of gravitation, field strength, and orbits, with potential and escape speed at HL.
• D.2 Electric and magnetic fields: Coulomb's law, field lines, electric field strength, and magnetic fields around currents, with potential at HL.
• D.3 Motion in electromagnetic fields: charges moving in uniform electric and magnetic fields, and the force on a current-carrying wire.
• D.4 Induction (HL only): magnetic flux, Faraday's and Lenz's laws, and generators.

Theme E: Nuclear and quantum physics

• E.1 Structure of the atom: the nuclear model, Rutherford scattering, and energy levels and spectra.
• E.2 Quantum physics (HL only): the photoelectric effect, photons, matter waves and wave-particle duality.
• E.3 Radioactive decay: alpha, beta and gamma decay, half-life, and binding energy.
• E.4 Fission: chain reactions and how a nuclear reactor is controlled.
• E.5 Fusion and stars: fusion in stars, stellar stability, luminosity, the Hertzsprung-Russell diagram and stellar evolution.

Topic names here follow the IB guide; your teacher's scheme of work may teach them in a different order. The IB itself encourages teaching across themes rather than in strict A-to-E sequence.

How IB Physics is assessed

There are two written papers and one internal assessment. A clean copy of the Physics data booklet is given to you in every paper, and you need a calculator.

• Paper 1: Paper 1A is multiple choice and Paper 1B is data-based questions on experimental work. At SL it lasts 1 hour 30 minutes for 45 marks; at HL, 2 hours for 60 marks. It is worth 36% at both levels.
• Paper 2: short-answer and extended-response questions. At SL it lasts 1 hour 30 minutes for 55 marks; at HL, 2 hours 30 minutes for 90 marks. It is worth 44%.
• Internal assessment: your own scientific investigation, marked by your teacher and moderated by the IB, worth 20% at both levels. It is marked out of 24. See our guide to IB Physics IA ideas and criteria.

Paper 1B is new in this syllabus and deserves its own practice. It gives you data from an experiment, often one you have not done, and asks you to process it: plot or read graphs, find gradients, handle uncertainties and draw conclusions.

Worked example: a Theme A question

A ball is thrown horizontally at 15 m s⁻¹ from a height of 20 m. Taking g = 9.8 m s⁻² and ignoring air resistance, how far from the base does it land?

• Vertical motion from rest: 20 = ½ × 9.8 × t², so t² = 4.08 and t = 2.02 s.
• Horizontal motion is at constant speed: distance = 15 × 2.02 = 30 m (2 s.f.).
• IB mark schemes reward the separate treatment of the two directions, so show both lines.

Worked example: a Theme B circuit

A cell of e.m.f. 6.0 V and internal resistance 0.50 Ω drives a current through a 2.5 Ω resistor. Find the current and the terminal potential difference.

• Total resistance = 2.5 + 0.50 = 3.0 Ω, so I = 6.0 / 3.0 = 2.0 A.
• Terminal p.d. = ε − Ir = 6.0 − 2.0 × 0.50 = 5.0 V.

Planning your two years

1. Build the maths early. Rearranging, vectors, logarithms, graph gradients and uncertainties run through every theme and through Paper 1B.
2. Keep the data booklet open while you practise. You will know where each equation sits by exam time.
3. Start IA thinking in the first year. Note experiments you enjoyed and questions they raised.
4. Mix themes in revision. Exam questions combine ideas, for example energy (A.3) with circuits (B.5), or fields (D) with circular motion (A.2).
5. Practise with past papers from 2025 onwards for the new format, and use older papers only for topics that are still on the syllabus.

Common mistakes

• Revising old-syllabus option topics that are no longer examined.
• Ignoring Paper 1B until the last month; data handling is a skill that takes time.
• Learning equations without knowing what each symbol means and its unit.
• Treating HL-only topics as optional extras when they appear in HL Paper 2.

Practice questions

Try each one before opening the answer.

Frequently asked questions

Are there still options in IB Physics?

No. The syllabus first assessed in 2025 removed the options. Every student studies Themes A to E, and HL adds depth and five HL-only subtopics.

Is IB Physics SL much easier than HL?

SL covers the same five themes with less depth and without the HL-only subtopics, and the papers are shorter. HL has 240 teaching hours against 150 for SL.

Can I use past papers from before 2025?

Yes, for topics still on the syllabus, but the format changed. Use 2025 papers and specimen papers to practise Paper 1B and the new structure.

Is a calculator allowed?

Yes. You need a calculator for both papers, and you get the data booklet in each one.

Key takeaways

• Five themes, A to E, for every student.
• HL adds five subtopics and more depth: 240 hours against 150.
• Paper 1 (36%) includes the new data-based Paper 1B.
• Paper 2 is 44% and the IA is 20%.
• The data booklet is provided in every paper.

Related guides

• IB Physics data booklet
• IB Physics IA ideas and criteria
• The equations of motion
• Simple harmonic motion