Download clean, printable lists of the most common mistakes students make — so you can fix them before they cost marks.
Each sheet is aligned to its exam board and built from recurring student errors highlighted in examiner reports and mark schemes.
What you get
A topic-by-topic mistakes list with a “do this instead” fix and a quick self-check.
How to use it
Review before past papers, then use the quick checks to catch errors under timed conditions.
Why it works
Many marks are lost on predictable slips: rounding, sign errors, units, and misreading commands.
Coverage by topic
Preview (up to 5 per topic)
15 total rows in download
| Topic | Common mistake / misconception | Do this instead | Quick check |
|---|---|---|---|
| Measurements | Confusing absolute, fractional and percentage uncertainty. | Absolute: ±Δx in same units. Fractional: Δx/x (no units). Percentage: (Δx/x)×100%. When multiplying/dividing, ADD fractional (or %) uncertainties. | Adding/subtracting: add absolute uncertainties. Multiplying/dividing: add fractional uncertainties. |
| Measurements | Quoting a calculated result to more sig figs than the least precise measurement. | Final answer cannot be more precise than your least precise input. Round to match the data with fewest significant figures. | Which input has fewest sig figs? Round your answer to match. |
| Mechanics | Saying an object in circular motion has no acceleration. | Circular motion: speed is constant but DIRECTION changes → velocity changes → centripetal ACCELERATION exists. a = v²/r, directed towards centre. | Circular motion: constant speed ≠ no acceleration. Direction change = acceleration. |
| Mechanics | Applying conservation of momentum to systems with external forces. | Momentum is conserved ONLY in closed systems (no external forces). Check for friction, gravity, normal force before applying conservation. | Is the system closed (no net external force)? If yes → momentum conserved. |
| Thermal Physics | Saying temperature is the same as thermal energy. | Temperature: measure of average kinetic energy per particle. Thermal energy: total internal energy. A large cold object can have more thermal energy than a small hot one. | Temperature = average KE per particle. Thermal energy = total KE of ALL particles. |
| Thermal Physics | Confusing specific heat capacity and specific latent heat. | SHC: Q = mcΔT (temperature CHANGES). Latent heat: Q = mL (temperature CONSTANT — change of state). Used for different situations. | Temperature changing? → Q = mcΔT. State changing at constant temperature? → Q = mL. |
| Waves | Saying intensity and amplitude are directly proportional. | Intensity ∝ Amplitude². Doubling the amplitude quadruples the intensity. This is a square relationship, not linear. | I ∝ A². Double amplitude → 4× intensity. |
| Waves | Confusing constructive and destructive interference conditions. | Constructive: path difference = nλ (whole number of wavelengths). Destructive: path difference = (n + ½)λ (half-wavelength out of phase). | Path difference whole number of λ → constructive. Half-integer λ → destructive. |
| Electricity | Saying current is used up in a resistor. | Current is NOT used up. Charge is conserved — the same current enters and leaves a resistor. ENERGY is converted (to heat) in the resistor. | Current (charge flow) is conserved. Energy is transferred. Current in = current out. |
| Electricity | Forgetting that resistance increases with temperature for metallic conductors. | For metals: as T increases, lattice ions vibrate more, increasing electron collisions → resistance increases. Opposite for semiconductors (NTC thermistors). | Metal: R increases with T. Semiconductor/thermistor: R decreases with T. |
| Fields | Saying gravitational field strength is always 9.81 N/kg. | g = 9.81 N/kg at Earth's surface only. It decreases with distance from Earth (g ∝ 1/r²). Always check whether the question involves surface or a different altitude. | Only 9.81 at surface. Above surface: g = GM/r² and decreases. |
| Fields | Confusing electric potential and electric field strength. | E = −dV/dr. Field strength = negative gradient of potential. Where potential is constant (equipotential), field strength is perpendicular to it. | E is the gradient (slope) of V. Where V is flat → E = 0 is wrong — check the gradient. |
| Atomic Physics | Saying electrons 'jump' to higher energy levels by emitting photons. | Electrons ABSORB photons to move to HIGHER energy levels (excitation). They EMIT photons when moving to LOWER energy levels. | Absorb photon → go up (excitation). Emit photon → go down (de-excitation). |
| Atomic Physics | Misapplying the photoelectric effect equation. | hf = φ + Ekmax. hf = photon energy. φ = work function. Ekmax = max kinetic energy of emitted electron. Intensity does NOT affect Ekmax — only frequency does. | Higher intensity → more electrons (higher current). Higher frequency → higher Ekmax. Not the other way. |
| Nuclear Physics | Saying nuclear fission and fusion both split atoms. | Fission: HEAVY nucleus splits into lighter ones (e.g. U-235). Fusion: LIGHT nuclei combine into heavier one (e.g. H + H → He). Opposite processes. | Fission = split (heavy → light). Fusion = join (light → heavier). Both release energy. |