AS Physics Formulas: Organise Revision and Check Worked Examples

Identify the examination board and year

There is no single universal list covering every course called AS Physics. This guide uses Cambridge International 9702 for examinations in 2025–2027 as a concrete reference. Its AS content is topics 1–11 plus practical skills. Use the official syllabus linked below to build the complete checklist for your examination year, and use your own board's specification if you study a different qualification. The selected formulas and worked examples here provide revision practice; they are not a replacement for every learning outcome, definition, diagram or practical requirement.

Separate supplied formulas from required understanding

The official syllabus includes its data-and-formula pages, and Cambridge's support guidance states that formula information appears in the theory question papers. Read the actual sheet for the relevant paper rather than assuming that a formula found on a revision website will be supplied. For each relationship in your notes, record the meaning and unit of every symbol, the conditions under which it applies and whether you can rearrange it. A formula sheet is useful only when you can recognize which quantities in a question correspond to its symbols.

Group motion, force and energy relationships

For constant acceleration along one dimension, useful relationships include v = u + at, s = ut + ½at² and v² = u² + 2as. Net force is ma for the constant-mass model, momentum is mv, and translational kinetic energy is ½mv². In an original practice case, u = 2 m/s, a = 3 m/s² and t = 4 s give v = 14 m/s and s = 32 m. For mass 2 kg, net force is 6 N and kinetic-energy gain is 192 J, matching net work 6 × 32.

Keep material and pressure quantities distinct

Density is mass divided by volume, pressure is normal force divided by area, and a hydrostatic pressure difference is ρgΔh for the stated fluid model. In deformation work, stress is force/area and strain is extension/original length; Young modulus is their ratio in the linear region. For an example force of 100 N on area 2.0 × 10⁻⁶ m², stress is 5.0 × 10⁷ Pa. If extension is 0.50 mm over an original length of 1.0 m, strain is 0.00050 and the corresponding modulus is 1.0 × 10¹¹ Pa.

Define the geometry in wave and interference formulas

Wave speed is fλ and frequency is 1/T. For double-slit interference, λ = ax/D uses slit separation a, fringe spacing x and screen distance D under the appropriate small-angle setup. With a = 0.50 mm, x = 2.0 mm and D = 2.0 m, wavelength is 5.0 × 10⁻⁷ m, or 500 nm. Converting both millimetre values before multiplication is essential. A diffraction grating instead uses d sin θ = nλ, with grating spacing d and integer order n; its geometry should not be substituted blindly into the double-slit expression.

Practise circuits with the connected quantities visible

For constant current, Q = It; potential difference is transferred energy per charge, V = W/Q. Resistance is V/I, while resistor power can be written VI, I²R or V²/R with consistent values for that component. Series resistances add; parallel resistances satisfy 1/R_total = Σ(1/R_i). In a simple example, 6 Ω and 3 Ω in parallel give 2 Ω. Across 12 V, total current is 6 A and total power is 72 W. Individual branch currents are 2 A and 4 A, providing a separate current-sum check.

Build revision checks that go beyond memorisation

After solving one example, change one input and predict the effect before recalculating. Doubling speed at fixed mass quadruples kinetic energy, while doubling a wire's length at unchanged material and area doubles its resistance. Include dimensional checks, graph interpretation and particle-physics conservation bookkeeping alongside numerical formulas. The local Physics Calculator evaluates expressions you supply; it does not know your exam board, choose a formula or mark a complete solution. Use explicit entries such as 1/(1/6+1/3) to check arithmetic, and retain your diagram, units, assumptions and syllabus reference in the written work.

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