OCR A-Level Physics equation sheet: A complete guide for 2026
OCR A-Level Physics (specification H556, also known as Physics A) gives you a booklet called the Data, Formulae and Relationships Booklet at the start of every paper. It contains the constants, equations and relationships you need across the entire course. You do not have to memorise the contents, but you do need to know your way around it.
The same booklet is provided for Paper 1 (Modelling Physics), Paper 2 (Exploring Physics) and Paper 3 (Unified Physics). It is identical across all three. Invigilators hand it out alongside the question paper, so there is nothing to download into the exam itself.
This guide walks through what is on the OCR A-Level Physics equation sheet, how it is structured, and the habits that turn the booklet from a safety net into a working tool. Most students who lose marks on calculation questions could have saved them with five minutes of revision time spent on the booklet itself.
Pages
8
of constants, equations, and relationships in the OCR A-Level Physics Data, Formulae and Relationships Booklet (H556), provided in every exam
What's on the OCR A-Level Physics equation sheet?
The booklet has three main parts. The first part is data, which means physical constants, conversion factors, and standard prefixes (giga, mega, micro, nano). The second part is formulae and relationships, which lists the equations you need by module. The third part is a short reminder of mathematical and geometric formulae that come up across the specification.
OCR organises the equations by module, with separate sections for Foundations of Physics, Forces and Motion, Electrons, Waves and Photons, Newtonian World and Astrophysics, and Particles and Medical Physics. The headings echo the modules in the specification, so once you have learned the layout the navigation is straightforward.
OCR also includes a Quanta section covering photons, the photoelectric effect and de Broglie waves, plus a Capacitors and Magnetic Fields section that pulls together the relevant electromagnetic equations. Values for the universal constants match the other boards, with c at 3.00 × 10⁸ m s⁻¹, h at 6.63 × 10⁻³⁴ J s, and e at 1.60 × 10⁻¹⁹ C.
Constants and physical data
OCR lists the universal constants near the start of the booklet, with values quoted to three significant figures. Use the booklet values during calculations rather than recalled values. The mark scheme model answers use exactly these figures, so your answer will line up with the expected response.
| Constant | Symbol | Value | Units |
|---|---|---|---|
| Speed of light in vacuum | c | 3.00 × 10⁸ | m s⁻¹ |
| Planck constant | h | 6.63 × 10⁻³⁴ | J s |
| Elementary charge | e | 1.60 × 10⁻¹⁹ | C |
| Electron mass | mₑ | 9.11 × 10⁻³¹ | kg |
| Proton mass | mₚ | 1.67 × 10⁻²⁷ | kg |
| Neutron mass | mₙ | 1.67 × 10⁻²⁷ | kg |
| Gravitational constant | G | 6.67 × 10⁻¹¹ | N m² kg⁻² |
| Permittivity of free space | ε₀ | 8.85 × 10⁻¹² | F m⁻¹ |
| Avogadro constant | Nₐ | 6.02 × 10²³ | mol⁻¹ |
| Molar gas constant | R | 8.31 | J K⁻¹ mol⁻¹ |
| Boltzmann constant | k | 1.38 × 10⁻²³ | J K⁻¹ |
| Stefan constant | σ | 5.67 × 10⁻⁸ | W m⁻² K⁻⁴ |
| Acceleration due to gravity (Earth) | g | 9.81 | m s⁻² |
The OCR booklet also lists the electronvolt (1 eV = 1.60 × 10⁻¹⁹ J) and the atomic mass unit (1 u = 1.66 × 10⁻²⁷ kg). Both come up in particle and nuclear questions. Use the booklet values rather than rounded ones from your notes, because the mark scheme is built around the booklet figures.
Equation list by topic
The tables below cover the most exam-relevant equations from each OCR module. The full booklet includes a handful of less-frequent relationships (e.g. impulse-time graphs, fluid mechanics) that are worth scanning at least once, but the equations below carry most of the marks across all three papers.
OCR uses standard physics notation throughout. Where OCR differs slightly from AQA or Edexcel in symbol choice, the booklet defines the variables explicitly underneath each equation.
Forces and motion
| Equation | Formula | Notes |
|---|---|---|
| Equation of motion (velocity) | v = u + at | u and v are initial and final velocity |
| Equation of motion (displacement) | s = ut + ½at² | Constant acceleration |
| Equation of motion (no time) | v² = u² + 2as | Useful when t is unknown |
| Newton's second law | F = ma | F is the resultant force |
| Weight | W = mg | Near a planet's surface |
| Work done | W = Fx cos θ | θ between F and direction of motion |
| Kinetic energy | Eₖ = ½mv² | Translational kinetic energy |
| Gravitational PE (uniform g) | ΔE = mgΔh | Only near Earth's surface |
| Power | P = W/t = Fv | Two useful forms |
| Efficiency | η = useful output / total input × 100% | Often as a percentage |
| Momentum | p = mv | Conserved in closed systems |
| Impulse | FΔt = Δp | Force × time = change in momentum |
Electricity
| Equation | Formula | Notes |
|---|---|---|
| Charge | Q = It | Coulombs |
| Potential difference | V = W/Q | Energy per unit charge |
| Resistance (Ohm's law) | V = IR | Definition of resistance |
| Resistivity | R = ρL/A | ρ depends on material and temperature |
| Electrical power | P = IV = I²R = V²/R | Three useful forms |
| Energy transferred | W = VIt | Joules |
| EMF and internal resistance | ε = I(R + r) | r is internal resistance of the cell |
Waves, quanta and photons
| Equation | Formula | Notes |
|---|---|---|
| Wave speed | v = fλ | v is wave speed, λ is wavelength |
| Period | T = 1/f | T in seconds |
| Refractive index | n = c / cₛ | cₛ is speed in the substance |
| Snell's law | n₁ sin θ₁ = n₂ sin θ₂ | Refraction at a boundary |
| Critical angle | sin C = 1/n | n is the refractive index of the denser medium |
| Double slit | λ = ax/D | a is slit separation, x is fringe spacing, D is slit-to-screen distance |
| Diffraction grating | d sin θ = nλ | n is the order |
| Photon energy | E = hf = hc/λ | Two useful forms |
| Photoelectric equation | hf = φ + KEₘₐₓ | φ is the work function |
| de Broglie wavelength | λ = h/p | p is momentum |
Further mechanics and fields
| Equation | Formula | Notes |
|---|---|---|
| Hooke's law | F = kx | k is the force constant |
| Elastic potential energy | E = ½Fx = ½kx² | Two equivalent forms |
| Young modulus | E = stress / strain | Equivalent to (FL)/(AΔL) |
| Centripetal acceleration | a = v²/r = ω²r | Always directed towards centre |
| Angular velocity | ω = 2π/T = 2πf | Radians per second |
| Newton's gravitation | F = Gm₁m₂/r² | Inverse square law |
| Gravitational field strength | g = GM/r² | Radial field around a point mass |
| Gravitational potential | V_g = −GM/r | Always negative |
| Coulomb's law | F = (1/4πε₀)(Q₁Q₂/r²) | Inverse square law for charges |
| Electric field (point charge) | E = (1/4πε₀)(Q/r²) | Radial field |
| Capacitance | C = Q/V | Farads = coulombs per volt |
| Capacitor energy | W = ½QV = ½CV² | Two useful forms |
| Capacitor discharge | Q = Q₀ e^(−t/RC) | RC is the time constant |
| Magnetic force on a wire | F = BIL sin θ | θ between B and current |
| Magnetic force on a charge | F = BQv sin θ | θ between B and v |
| Faraday's law | ε = −N(dΦ/dt) | N is number of turns |
Simple harmonic motion
| Equation | Formula | Notes |
|---|---|---|
| SHM (defining) | a = −ω²x | Defining relation |
| SHM displacement (cosine) | x = A cos(ωt) | When max displacement at t = 0 |
| SHM velocity (max) | v_max = ωA | At zero displacement |
| Period of a mass-spring | T = 2π √(m/k) | Hooke's law applies |
| Period of a simple pendulum | T = 2π √(L/g) | Small-angle approximation |
Thermal, nuclear and astrophysics
| Equation | Formula | Notes |
|---|---|---|
| Specific heat capacity | E = mcΔθ | θ is temperature change |
| Specific latent heat | E = mL | L for fusion or vaporisation |
| Ideal gas equation | pV = nRT | Also pV = NkT |
| Kinetic theory of gases | pV = ⅓Nm⟨c²⟩ | N is number of molecules |
| Average KE of a molecule | ½m⟨c²⟩ = (3/2)kT | Links temperature to molecular motion |
| Radioactive decay | N = N₀ e^(−λt) | λ is the decay constant |
| Activity | A = λN | Becquerels |
| Half-life | t_½ = ln 2 / λ | Time for activity to halve |
| Mass-energy equivalence | ΔE = c²Δm | Energy from nuclear reactions |
| Stefan's law | L = 4πr²σT⁴ | Total power radiated by a star |
| Wien's displacement law | λ_max T = 2.898 × 10⁻³ m K | Peak wavelength of a black body |
| Hubble's law | v = H₀d | v is recession velocity, d is distance |
A common mistake OCR students make with the booklet is leaving it shut until they get stuck. Open it from question one. Examiners give a substitution mark for the correct equation, separately from the final answer. Writing the equation down before plugging in numbers protects marks even when the arithmetic later goes wrong.
How to use the equation sheet effectively
Treat the OCR booklet as a working document. The students who get the most from it have spent weeks practising with it, not just opened it for the first time on exam day.
The most useful habit is downloading the official PDF from the OCR website and printing it out. Slot it next to your question paper for every past paper attempt. Within two weeks you will know which module each equation lives under, which saves real seconds when the clock is ticking.
The second habit is writing the equation down at the top of every calculation. The mark scheme awards a substitution mark for stating the right equation, separately from the arithmetic mark. Even if your final number is off, you keep that first mark.
The third habit is checking units before you start computing. R is in J K⁻¹ mol⁻¹, σ is in W m⁻² K⁻⁴, and both demand kelvin. One of the most common arithmetic mistakes in astrophysics questions is a kelvin-to-Celsius slip, which destroys the answer by a factor of millions because temperature is to the fourth power.
Common mistakes
The first common mistake is reaching for a similar-looking equation. OCR lists several energy and momentum expressions close together. Underline what the question is asking for before you turn to the booklet. The right equation jumps out once you know which variable you are solving for.
The second is rearranging on the calculator. Some booklet equations are only given in canonical form. To find a different variable you must rearrange on paper before substituting. Trying to do it inline on the calculator is where signs flip and powers invert.
The third is failing to convert. Electron volts, atomic mass units, light years, parsecs and astronomical units all need converting to SI before they enter a calculation. The booklet lists every conversion factor you need, and most students who lose marks here simply did not check the data page.
The fourth, and most costly on Paper 3, is dropping signs on gravitational potential. The booklet writes V_g = −GM/r with the negative explicit. Students copy the formula but lose the sign. The mark scheme penalises both magnitude and sign in field questions.
OCR A-Level Physics equation sheet checklist
Build real fluency with the booklet before exam day. Tick these off over the final few weeks.
- Download the official Data, Formulae and Relationships Booklet PDF from OCR
- Use it during every past paper attempt, not only on difficult topics
- Learn the module layout so you can navigate to each topic instantly
- Write each equation down before substituting numbers
- Check units carefully, especially for R, σ and ε₀
- Rearrange the canonical form on paper rather than the calculator
- Keep the minus sign on gravitational potential
- Skim the conversions page before any nuclear, particle or astrophysics question
