IB DP Physics · Exam special · SL & HL · checked against the data booklet for first assessment 2025 · ~8 min read
IB Physics Data Booklet: Equations Not Given and How to Use It
What the IB Physics data booklet (first assessment 2025) contains, the equations and facts it leaves out that you must know or derive, and how to use the booklet quickly in Papers 1 and 2.
What the booklet containsConstants & conversionsEquations not given (SL)Equations not given (HL)Quick derivationsSymbols & unitsUsing the booklet fast
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No tag = SL and HLHL ONLY HL students onlyDATA BOOKLET given in the examM1A1 how marks are awardedhighlight = comes up again and againHANDY worth memorisingTest yourself at the end
In 30 seconds
- The data booklet is available in every Physics paper. It has the constants, unit conversions, circuit symbols and the equations for each topic, with the HL-only equations listed separately.
- It gives magnitudes only. There are no vector signs and no directions: you supply those (for example, which way a force or current acts).
- Several common results aren't in it. You either memorise them or derive them in one or two lines from equations that are.
By the end you can
- Know what the data booklet gives you, topic by topic.
- Learn or derive the equations it leaves out.
- Use the booklet quickly and choose the right symbols and units.
1What the booklet contains
General pages
| Section | What it gives |
|---|---|
| Mathematical equations | Areas and volumes of simple shapes; resolving a vector into components (A cos θ, A sin θ); tan θ and sin²θ + cos²θ = 1 |
| Uncertainties | Rules for sums, products/quotients and powers |
| Fundamental constants | g, G, NA, R, kB, σ, k, ε₀, μ₀, c, h, e, masses of the electron, proton and neutron (kg, u and MeV c⁻²), u, solar constant, Fermi radius |
| Multipliers | peta (10¹⁵) down to femto (10⁻¹⁵) |
| Unit conversions | Radians ↔ degrees, °C ↔ K, light year, parsec, AU, kWh, hc in J m and eV m |
| Other | Circuit symbols; the electromagnetic spectrum with wavelengths |
Topic equations
| Theme | SL and HL | HL only |
|---|---|---|
| A Space, time and motion | suvat; friction; Hooke's law; drag (6πηrv); buoyancy; momentum and impulse; centripetal acceleration; work, KE, GPE, EPE, power, efficiency | Rigid bodies (torque, angular suvat, moment of inertia, angular momentum, rotational KE); Galilean and special relativity |
| B Particulate nature of matter | Density; average KE of molecules; specific heat and latent heat; conduction; Stefan–Boltzmann; intensity b = L/4πd²; Wien; emissivity; albedo; gas laws; current, pd, resistance, resistivity, power, series/parallel, emf and internal resistance | First law, work by a gas, internal energy change, entropy (ΔQ/T and kB ln Ω), adiabatic pV5/3, Carnot efficiency |
| C Wave behaviour | SHM a = −ω²x, periods of pendulum and mass–spring, v = fλ, Snell's law, interference conditions, double slit s = λD/d, Doppler for light | SHM x, v and energy equations; single slit θ = λ/b; grating nλ = d sin θ; Doppler for sound |
| D Fields | Newton's gravitation, g = GM/r², Coulomb's law, E = F/q, E = V/d, magnetic forces on charges, wires and parallel wires | Gravitational and electric potential and potential energy, field = −gradient, escape and orbital speed; induction: flux, Faraday, ε = BvL |
| E Nuclear and quantum | E = hf, E = mc², parallax distance | Nuclear radius, Bohr energy levels and angular momentum, photoelectric equation, de Broglie, Compton shift, exponential decay, activity, half-life |
2Equations NOT in the booklet: SL and HL
Mechanics
| Result | How to get it |
|---|---|
| Conservation of momentum: total p before = total p after | Principle; learn it |
| Elastic collision: total KE is also conserved | Principle |
| Impulse = area under a force–time graph | From J = FΔt for a varying force |
| Projectiles: horizontal velocity constant, vertical a = −g | Resolve with A cos θ, A sin θ, then suvat for each direction separately |
| Work done = area under a force–displacement graph | From W = Fs for a varying force |
| Weight component down a slope = mg sin θ; normal force = mg cos θ | Resolve the weight |
Waves
| Result | How to get it |
|---|---|
| Refractive index n = c/v | Snell's law with medium 1 as vacuum |
| Critical angle: sin c = n₂/n₁ | Snell's law with θ₂ = 90° |
| String or pipe open at both ends: L = nλ/2 | Draw the standing wave: nodes (or antinodes) at both ends |
| Pipe closed at one end: L = (2n − 1)λ/4 (odd harmonics only) | A node at the closed end, an antinode at the open end |
| Intensity ∝ amplitude² | Learn it |
| f = 1/T and ω = 2πf | ω = 2π/T is given; rearrange |
Fields and circuits
| Result | How to get it |
|---|---|
| Potential divider: Vout = Vin × R₂/(R₁ + R₂) | Same current through both resistors |
| Terminal pd: V = ε − Ir | Rearrange ε = I(R + r) |
| Field of a long straight wire: B = μ₀I/(2πr) | From the given force between parallel wires, F/L = μ₀I₁I₂/(2πr), and F = BIL: the field of wire 1 at wire 2 is B = μ₀I₁/(2πr) |
| Radius of a charge's circle in a B-field: r = mv/(qB) | qvB = mv²/r |
| Kepler's third law: T² = 4π²r³/(GM) | GMm/r² = m(4π²r/T²) |
| Orbital speed v = √(GM/r) (given at HL; derive at SL if needed) | GMm/r² = mv²/r |
Thermal, nuclear and quantum
| Result | How to get it |
|---|---|
| Half-lives (SL): after n half-lives N = N₀(½)ⁿ | Halve n times |
| Binding energy = mass defect × c² (931.5 MeV per u) | E = mc² with the u conversion given |
| Photon energy in eV: E = 1.24 × 10⁻⁶ / λ (λ in m) | hc in eV m is given |
| Energy level transition: ΔE = hf | E = hf |
| Conservation of A and Z (charge) in nuclear equations | Principle |
| Decay products: α = ⁴₂He, β⁻ emits an electron + antineutrino, β⁺ a positron + neutrino | Learn them |
3Quick derivations worth practising
Worked example
Derive Kepler's third law for a circular orbit.
- Gravity provides the centripetal force: GMm/r² = mv²/r
- v = 2πr/T, so GM/r² = 4π²r/T²
- T² = (4π²/GM) r³, so T² ∝ r³
Worked example
Find the critical angle for glass (n = 1.50) in air.
- sin c = n₂/n₁ = 1.00/1.50 = 0.667
- c = 41.8°
Worked example
A pipe closed at one end is 0.85 m long. Find the fundamental frequency if the speed of sound is 340 m s⁻¹.
- L = λ/4 ⇒ λ = 3.4 m
- f = v/λ = 340/3.4 = 100 Hz
4Constants and symbols
- g = 9.8 m s⁻² in the booklet. Examiners accept 9.81 too; use the value the question gives if there is one.
- Use the booklet's symbols: Ek, Ep, FH for Hooke's law, ε for emf. Defining your own is fine, but say what they are.
- Know the units of each constant to check your answers: G in N m² kg⁻², σ in W m⁻² K⁻⁴, kB in J K⁻¹.
- Temperatures in kelvin for gas laws, Stefan–Boltzmann and Wien. The booklet gives K = °C + 273.
- Electronvolts: 1 eV = 1.60 × 10⁻¹⁹ J (the elementary charge e is given).
5Using the booklet fast
- Learn the order: general pages first, then themes A to E, each with SL equations followed by "Additional higher level".
- Write the equation you are using before substituting. Copying it from the booklet isn't enough on its own; the substitution earns the method mark.
- Check which symbol means what. L is length in some equations, luminosity in b = L/4πd², and angular momentum in A.4.
Common mistakeSearching for an equation that isn't there. Learn the "not given" tables above so you know at once whether to derive.
Linking questionFor the physics behind these results see C.4 Standing waves and resonance, D.1 Gravitational fields and D.3 Motion in electromagnetic fields. For exam technique see Paper 2 answers.
Test yourself — cover the answers first
Quick check
- Is the critical angle formula in the data booklet?
- What length is a closed pipe for its fundamental?
- Is Kepler's third law in the data booklet?
- What value of g does the data booklet give?
- Is the B-field of a long straight wire given?
Show answers
- no; use sin c = n₂/n₁ from Snell's law
- λ/4
- no; derive it from gravity = centripetal force
- 9.8 m s⁻²
- no; B = μ₀I/(2πr)
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