A-Level Physics Revision Notes by Topic: Equations, Definitions, and Typical Questions

Overview

This article brings together high-yield a level physics revision notes by topic, with a practical focus on equations, definitions, and typical exam questions. The aim is not to replace your course notes, but to help you revise with better structure. For each topic, check three things:

• Equations: Can you recall them, rearrange them, and apply them with correct units?
• Definitions: Can you give concise, standard phrasing for key terms?
• Typical questions: Can you recognize the pattern of common exam tasks and respond methodically?

If you want revision that actually sticks, treat each topic as a small system. Learn the meaning first, then the formula, then the worked method, then the common traps. That approach is much more reliable than trying to memorize disconnected facts.

A useful rule is this: if you cannot explain what a quantity means physically, you probably do not yet know how to use its equation safely. Physics rewards understanding. The formula is only the compressed form of the idea.

These notes are written broadly enough to be useful across common A-Level specifications, but you should still match wording and required formula knowledge to your own course. Where a specification differs, use this page as the revision framework and adapt the details from your class materials.

Checklist by scenario

Use this section as a revision-by-topic checklist. Return to it topic by topic, not just once.

1. Mechanics

What to know: scalar vs vector, displacement, velocity, acceleration, force, resultant force, momentum, impulse, work done, power, efficiency.

Core equations: SUVAT equations, F = ma, W = Fs cos θ where relevant, P = E/t, P = Fv, p = mv, FΔt = Δp, kinetic energy and gravitational potential energy equations where included in your course.

Definitions to learn precisely: acceleration as rate of change of velocity; momentum as the product of mass and velocity; impulse as change in momentum; work done as energy transferred by a force.

Typical questions:

• Interpret a velocity-time or displacement-time graph.
• Find stopping distance or braking force.
• Use conservation of momentum in collisions and explosions.
• Compare momentum conservation with kinetic energy changes.
• Resolve forces on an incline or in equilibrium.

Revision check: Can you choose the correct SUVAT equation without substituting into all of them first? Can you tell when momentum is conserved and when energy is not?

2. Materials

What to know: density, stress, strain, Young modulus, elastic and plastic behavior, limit of proportionality.

Core equations: density, stress, strain, and Young modulus relationships.

Definitions: stress as force per unit cross-sectional area; strain as extension divided by original length; Young modulus as stress divided by strain within the proportional region.

Typical questions:

• Calculate extension of a wire from dimensions and material properties.
• Interpret force-extension graphs.
• Explain what happens when a material passes the elastic limit.

Revision check: Make sure you can distinguish between extension and total length, and between proportional limit and elastic limit.

3. Waves

What to know: transverse and longitudinal waves, displacement, amplitude, wavelength, period, frequency, phase difference, polarization, stationary waves, diffraction, interference.

Core equations: v = fλ, path difference conditions for constructive and destructive interference where required.

Definitions: wavelength as the distance between points in phase; frequency as number of oscillations per second; stationary wave as the superposition of two waves traveling in opposite directions producing nodes and antinodes.

Typical questions:

• Use wave speed, frequency, and wavelength together.
• Explain interference patterns in terms of path difference.
• Sketch and label stationary waves.
• Compare progressive and stationary waves.

Revision check: Can you explain phase difference in words, not just calculate it? Can you describe why stationary waves do not transfer energy in the same way as progressive waves?

For related visual explanations, see Optics Ray Diagrams Explained and Simple Harmonic Motion Explained.

4. Electricity

What to know: charge, current, potential difference, resistance, resistivity, emf, internal resistance, power, energy, series and parallel circuits.

Core equations: Q = It, V = IR, resistance combinations, power equations, resistivity relationships, ε = I(R + r) in equivalent form depending on notation.

Definitions: current as rate of flow of charge; potential difference as work done per unit charge; emf as energy supplied per unit charge by a source.

Typical questions:

• Analyze a simple circuit with multiple resistors.
• Find terminal pd using internal resistance.
• Interpret current-voltage graphs for different components.
• Explain why resistance changes with temperature for certain materials.

Revision check: Can you state the difference between emf and potential difference clearly? Can you keep track of units for charge, current, and energy transfer?

For step-by-step practice, see Ohm's Law and Basic Circuit Problems, Capacitors and RC Circuits Explained, and Magnetic Force and Fields.

5. Further mechanics, circular motion, and oscillations

What to know: centripetal acceleration, centripetal force, angular speed, simple harmonic motion, displacement, velocity, acceleration in SHM, energy changes in oscillations.

Core equations: centripetal force and acceleration relations, SHM equations such as a = -ω²x, period-frequency relation.

Definitions: SHM as oscillation in which acceleration is proportional to displacement and directed toward the equilibrium position.

Typical questions:

• Explain the direction of centripetal force.
• Find speed or period in circular motion.
• Interpret displacement-time, velocity-time, or acceleration-time graphs in SHM.
• Explain why maximum speed and maximum acceleration do not occur at the same position.

Revision check: Can you link the equation for SHM to the physical motion? Can you state where speed, displacement, and acceleration are maximum?

6. Thermal physics and gases

What to know: internal energy, specific heat capacity, specific latent heat, absolute temperature, ideal gas assumptions, pressure-volume relationships.

Core equations: heating equations, ideal gas equation in the form used by your course, efficiency where included.

Definitions: internal energy as the total random kinetic and potential energy of particles; absolute zero as the temperature at which particles have minimum possible internal energy in the model used.

Typical questions:

• Calculate energy needed for temperature change or change of state.
• Interpret pressure-volume graphs.
• Explain gas behavior using particle motion.
• State assumptions behind the ideal gas model.

Revision check: Can you separate temperature change from phase change questions? Can you explain macroscopic gas behavior with microscopic particle ideas?

A useful companion is Thermodynamics Formula Sheet.

7. Fields

What to know: gravitational field strength, electric field strength, field lines, potential, inverse-square behavior.

Core equations: force and potential equations in the forms given on your specification, definitions such as field strength as force per unit mass or force per unit charge.

Definitions: gravitational field strength as force per unit mass; electric field strength as force per unit positive charge; potential as work done per unit mass or per unit charge depending on context.

Typical questions:

• Sketch or interpret field patterns.
• Compare field strength and potential graphs.
• Use inverse-square reasoning carefully.
• Explain why potential can be zero at a point while field strength is not, or vice versa in some contexts.

Revision check: Make sure you can distinguish field strength from potential. This is a frequent source of lost marks.

8. Nuclear and particle physics

What to know: isotopes, nucleon number, proton number, activity, decay constant, half-life, quarks, leptons, hadrons, exchange particles, antimatter, photoelectric effect or other modern physics topics where included.

Core equations: decay relationships, activity definitions, energy equations such as E = mc² where required.

Definitions: half-life as the average time for the number of undecayed nuclei, or the activity, to halve; activity as decay rate.

Typical questions:

• Read decay graphs and calculate half-life.
• Complete particle interaction equations.
• Explain conservation laws in nuclear processes.
• Compare stable and unstable nuclei qualitatively.

Revision check: Can you apply conservation of charge, nucleon number, lepton number, and energy when relevant?

9. Practical skills and data handling

What to know: uncertainties, percentage uncertainty, systematic and random error, gradient, intercept, significant figures, graph choice, control variables.

Core ideas: many marks come from method and evaluation rather than difficult theory.

Definitions: random uncertainty as variation causing scatter; systematic error as consistent offset in one direction; precision as the degree of resolution or repeatability.

Typical questions:

• Suggest improvements to an experiment.
• Calculate gradient and identify physical meaning.
• Combine uncertainties sensibly.
• Explain why a graph has been linearized.

Revision check: Can you explain how changing a method reduces uncertainty, rather than just saying it makes results more accurate?

This is where many students gain steady marks. See Physics Lab Report Checklist for a practical review framework.

What to double-check

Before you move on from any topic, check the following points carefully.

• Units: Many a level physics equations only work cleanly when values are in standard SI units. Convert cm to m, g to kg, and minutes to seconds before substituting.
• Definitions: Do not rely on vague memory. In exams, definitions often need standard wording. Write them out and compare with your class notes.
• Symbols: The same letter can mean different things in different topics. Know whether V means volume or potential difference from context.
• Rearrangement: If you know the formula but struggle to rearrange it under pressure, that is a revision task, not a minor weakness.
• Graph meaning: Revise what the gradient and area under the graph represent. This appears across mechanics, electricity, and thermal physics.
• Command words: “State,” “define,” “calculate,” “explain,” and “show that” each require a different style of answer.
• Calculator discipline: Keep enough significant figures during working, then round only at the end unless instructed otherwise.

A good self-test is to pick one topic and answer these four prompts without notes: What are the key equations? What do the main quantities mean? What graph shapes appear? What mistakes am I likely to make?

Common mistakes

Strong students often lose marks in predictable ways. If you want your physics revision by topic to be efficient, build your revision around these errors.

• Memorizing formulas without knowing conditions of use. Example: using SUVAT in situations with non-constant acceleration.
• Confusing similar definitions. Common pairs include velocity and acceleration, emf and potential difference, field strength and potential, stress and force.
• Ignoring direction in vector quantities. Momentum, force, velocity, and acceleration need signs or clear vector reasoning.
• Writing generic explanations. Examiners reward precise physics, not long paragraphs with weak wording.
• Forgetting assumptions. Ideal models, negligible resistance, uniform fields, and isolated systems matter.
• Overlooking graph interpretation. Many questions are easier once you identify whether the graph asks for a gradient, area, trend, or comparison.
• Weak practical answers. “Repeat the experiment” is rarely enough. Say what should be repeated, why, and how the repeats improve reliability.

One of the best ways to avoid repeated mistakes is to keep an error log. After each practice set, record the topic, the mistake, the correct method, and the trigger that should have warned you. This turns past errors into revision material.

If you also study other courses, compare structures rather than trying to merge every detail. Our AP Physics Revision Hub, IB Physics Revision Guide, and GCSE Physics Equations List may help if you teach or revise across specifications.

When to revisit

This resource works best as a living checklist, not a one-time read. Revisit it at specific points in your revision cycle:

• At the start of a topic: to see the big picture before details accumulate.
• After finishing class notes: to convert passive notes into active recall prompts.
• Before mocks or end-of-term tests: to identify missing definitions and weak formula recall.
• During past paper practice: to diagnose which topic is causing repeated losses of marks.
• In final exam season: to do short, high-frequency reviews of equations, definitions, and standard question types.

A practical routine is to split your revision into three passes. On pass one, check understanding. On pass two, practice calculations and explanations. On pass three, focus only on mistakes and timing. Each time you revisit these notes, update your own list of weak spots underneath each topic heading.

If your workflow changes, update the way you use the checklist. For example, if you move from topic revision to mixed-paper practice, stop revising in isolated chapters only. Start using these notes to spot patterns across topics: graph skills, energy ideas, conservation laws, and proportional reasoning.

Action plan: Choose your next topic, write out its key equations from memory, define three central terms in one sentence each, then answer two typical questions without notes. If any step feels slow or uncertain, that topic goes back onto your revision list. Done regularly, this method turns scattered revision into a structured system you can trust.