Cambridge IGCSE Physics (0625): Every Equation You Need to Know
IGCSE Physics equations are the most efficient marks available in Cambridge 0625. The full set is small, entirely learnable, and appears in some form in nearly every question that carries more than two marks. This is the complete list, organised by topic, with the errors students make on each.
Does Cambridge IGCSE Physics give you the equations?
Cambridge does not supply a general equation sheet of the kind now used in some UK GCSE papers; the syllabus expects recall, with certain relationships provided within individual questions. Confirm the position in the syllabus for your exam year, and in either case learn them — selection and rearranging are what the marks are for.
What we see on our own learning portal: Cambridge IGCSE Physics drew 962 visitors to Tutopiya’s learning portal over the 30 days to 5 November 2026, placing it among the five largest subject audiences on the portal. (Tutopiya learning portal data, 30 days to 5 November 2026.)
Motion, forces and energy
| Quantity | Relationship | Units |
|---|---|---|
| Speed | speed = distance ÷ time | m/s |
| Acceleration | acceleration = change in velocity ÷ time | m/s² |
| Force | force = mass × acceleration | N |
| Weight | weight = mass × gravitational field strength | N |
| Density | density = mass ÷ volume | kg/m³ or g/cm³ |
| Momentum | momentum = mass × velocity | kg m/s |
| Impulse | impulse = force × time = change in momentum | N s |
| Moment | moment = force × perpendicular distance from pivot | N m |
| Work done | work = force × distance moved in direction of force | J |
| Power | power = work done ÷ time | W |
| Kinetic energy | KE = ½ × mass × velocity² | J |
| Gravitational PE | GPE = mass × g × height | J |
| Efficiency | useful output energy ÷ total input energy × 100 | % |
Where marks go: using mass instead of weight in force problems; forgetting to square the velocity in kinetic energy; measuring the moment distance along the force rather than perpendicular to it.
Pressure and thermal physics
| Quantity | Relationship | Units |
|---|---|---|
| Pressure | pressure = force ÷ area | Pa |
| Pressure in a liquid | pressure = density × g × depth | Pa |
| Gas law | pV = constant at constant temperature | — |
| Thermal energy | energy = mass × specific heat capacity × temperature change | J |
Where marks go: using the wrong area (total versus contact area); using depth below the surface incorrectly; forgetting that the gas law relationship requires constant temperature and a fixed mass of gas.
Waves
| Quantity | Relationship | Units |
|---|---|---|
| Wave speed | speed = frequency × wavelength | m/s |
| Frequency | frequency = 1 ÷ time period | Hz |
| Refractive index | n = sin i ÷ sin r | no unit |
| Critical angle | sin c = 1 ÷ n | degrees |
Where marks go: measuring angles from the surface rather than from the normal. Every refraction angle in physics is measured from the normal, and this single convention accounts for a large share of lost marks in the optics questions.
Electricity and magnetism
| Quantity | Relationship | Units |
|---|---|---|
| Charge | charge = current × time | C |
| Potential difference | V = I × R | V |
| Electrical power | P = V × I, and P = I²R | W |
| Electrical energy | energy = power × time, or E = IVt | J |
| Resistors in series | R total = R1 + R2 + … | Ω |
| Resistors in parallel | 1/R total = 1/R1 + 1/R2 + … | Ω |
| Transformer | Vp ÷ Vs = Np ÷ Ns | — |
Where marks go: parallel resistance — students calculate 1/R and give that as the answer, forgetting to invert at the end. Also: confusing the primary and secondary sides of the transformer equation.
Nuclear physics
| Quantity | Relationship |
|---|---|
| Half-life | the time for half the undecayed nuclei to decay |
| Activity | decreases by half each half-life |
Where marks go: half-life calculations done by guesswork rather than by halving systematically. Draw the table: time, number of half-lives, remaining activity.
How to learn them properly
Reciting the list does not build the examined skill. Do this instead.
1. Rearrange everything. Take each equation and write it rearranged for every variable. Twenty minutes, and it converts recall into usable fluency.
2. Learn the units with the equation. Not separately. The unit is part of the relationship.
3. Practise selection. The hard part of a physics question is not the algebra; it is knowing which relationship applies. Take twenty past questions and, without solving them, write only which equation you would use. Check against the mark scheme.
4. Watch the prefixes. Kilo, milli, centi, micro and mega appear constantly. Convert to SI units before substituting, every time.
5. Show the full working. Equation, substitution, answer, unit. Cambridge awards method marks, so a wrong final answer with visible correct method usually recovers most of them.
A one-week equation plan
| Day | Work |
|---|---|
| 1 | Motion, forces and energy: write out, rearrange, test |
| 2 | Pressure and thermal: write out, rearrange, test |
| 3 | Waves: write out, rearrange, plus ten refraction questions |
| 4 | Electricity: write out, rearrange, plus circuit calculations |
| 5 | Nuclear and revision of days 1 to 4 |
| 6 | Selection drill: forty past questions, identify the equation only |
| 7 | Twenty full calculation questions, timed, marked |
For related material, see how Cambridge IGCSE Physics students can use formula sheets without memorising blindly.
Sources and a caveat
The relationships listed are drawn from the Cambridge IGCSE Physics (0625) syllabus published by Cambridge International. Syllabus content and the list of relationships students are expected to recall are revised between cycles — download the syllabus for your exam year and check the list against it. Core and Extended candidates are expected to know different subsets. Mark schemes and examiner reports for recent series show how method marks are awarded.
Primary sources
- Cambridge IGCSE Physics (0625) syllabus
- Cambridge International — Cambridge IGCSE
- Cambridge International — programmes and qualifications
Portal figures are Tutopiya learning portal data read from the Learning Portal growth and health dashboard on 6 November 2026, comparing the 30 days to 5 November 2026 with the preceding 30 days.
Next step: write every equation on this page from memory, then check it against your syllabus. The ones you missed are your week’s work — and they are almost certainly the ones costing you marks in mock papers. For targeted practice, an IGCSE Physics tutor can drill equation selection with past questions.
Frequently asked questions
Are equations given in the Cambridge IGCSE Physics exam? +
Cambridge IGCSE Physics does not supply a general equation sheet in the way some UK GCSE papers now do. Students are expected to recall the equations in the syllabus, though some relationships are given within individual questions. Check the current syllabus for your exam year.
How many equations are there in IGCSE Physics 0625? +
Around 25 to 30 relationships across the syllabus, depending on how you count. Most are short and the set is entirely learnable in a few focused sessions, which makes them among the most efficient marks on the paper.
What is the most commonly misused equation in IGCSE Physics? +
The energy equations. Students confuse kinetic energy with gravitational potential energy, or use mass where weight is required. The second most common error is using the wrong form of the density or pressure relationships.
Do I need to memorise units as well as equations? +
Yes. Unit errors are among the most common avoidable mark losses in IGCSE Physics. Each equation should be learned with the unit of every quantity in it.
How should I learn the equations? +
By rearranging rather than reciting. Take each equation and write it rearranged for every variable. That builds the skill the exam actually tests, which is selecting and manipulating the right relationship.
How many students use Tutopiya's Cambridge IGCSE Physics resources? +
Cambridge IGCSE Physics drew 962 unique visitors to Tutopiya's learning portal in the 30 days to 5 November 2026, placing it among the five largest subject audiences on the portal. Figures come from Tutopiya's own learning portal analytics, read from the Learning Portal growth and health dashboard on 6 November 2026.
Ready to Excel in Your Studies?
Get personalised help from Tutopiya's expert tutors. Whether it's IGCSE, IB, A-Levels, or any other curriculum — we match you with the perfect tutor and your first session is free.
Book Your Free TrialWritten by
Mahira Kitchil
Project Head of AI Buddy
Mahira Kitchil is Project Head of AI Buddy at Tutopiya, where she works with schools and families across the UK, Malaysia, India and the Gulf. She follows Cambridge, Pearson Edexcel, AQA, OCR and IB announcements as they land in each market, and writes these guides from published syllabuses, board timetables and regulator guidance rather than second-hand summaries.
Related Articles
AQA GCSE Maths Paper 1 (Non-Calculator): The Topics That Come Up Most
What comes up most on AQA GCSE Maths Paper 1, the non-calculator paper: the recurring topics at Foundation and Higher, the skills you cannot do without, and how to revise them.
AQA GCSE Biology Required Practicals: The Complete List With Exam-Style Questions
All AQA GCSE Biology required practicals in one place, with the variables, common errors and the exam-style questions that come up most in Paper 1 and Paper 2.
Cambridge AS Level Accounting (9706): Where Students Lose the Most Marks
The most common mark-losing errors in Cambridge AS Level Accounting 9706, from format and presentation to adjustments and ratio interpretation, and how to fix each one.