Top Mistakes OxfordAQA IGCSE Physics Students Make (and How to Avoid Them)

Every recurring error in physics has a diagnosable cause and a specific fix. That's the approach I want to take here rather than a vague list of "be more careful" advice. oxfordaqa igcse physics common mistakes tend to cluster into a small number of patterns: misread command words, calculation slips, incomplete explanations, timing failures and a handful of topic-specific misconceptions that show up again and again. Work through the pattern, understand the mechanism behind it, and the fix usually follows naturally.

Below, each oxfordaqa igcse physics mistakes is broken down the same way: the wrong approach, why it costs marks, and the correct technique to replace it with. I've drawn the examples from the topics where these oxfordaqa igcse physics errors show up most consistently: Electrical Circuits, Energy Transfers, Conservation and Dissipation of Energy, Motion, Energy Transfers and Particle Motion, and Forces and Their Interactions.

Misread Command Words

The wrong approach: treating "state," "describe" and "explain" as interchangeable, and writing roughly the same style of answer regardless of which word is used.

Why it loses marks: each command word sets a different bar. "State" wants a short fact with no justification. "Describe" wants what happens, in sequence, without necessarily saying why. "Explain" wants the underlying physics reasoning, the why, not just the what. A candidate who writes a "describe"-level answer to an "explain" question is often missing exactly the marks reserved for the reasoning.

The correct technique: before writing anything, underline the command word and ask yourself what category of answer it demands. For "explain a change in resistance," don't stop at "the resistance increases." Continue to the mechanism: as current increases through a filament lamp, the filament heats up, the ions in the metal vibrate more vigorously, collisions with the flow of electrons increase, and resistance rises as a result. That second half of the answer is where the marks for "explain" actually sit.

Calculation Slips

The wrong approach: jumping straight to a final numerical answer without writing down the equation or the substitution.

Why it loses marks: mark schemes very often award marks separately for selecting the correct equation, for substituting the given values correctly, and for the final answer. Skip the first two steps and get the number wrong, and there's nothing left to award; show the working and get the number wrong, and there's often still a mark or two available.

Worked example. Calculate the resistance of a component that has a current of 0.5 A flowing through it when the potential difference across it is 6 V.
Wrong approach: writing "R = 12 Ω" with no working. If a value is transcribed incorrectly from the question, there's no partial credit to fall back on.
Correct technique: V = I × R, so R = V ÷ I = 6 ÷ 0.5 = 12 Ω. Every step is visible, and the unit is included.

A closely related slip is forgetting units, or mixing them within a single calculation, such as combining a time given in minutes with a rate given per second without converting first. Get into the habit of writing the unit next to every value the moment you copy it from the question, before you do any arithmetic at all.

Incomplete Explanations

The wrong approach: giving one correct idea in an explanation and stopping there, when the question and the number of marks available clearly call for a connected chain of reasoning.

Why it loses marks: a multi-mark explain question is usually built from a sequence of linked statements, and each link typically corresponds to a mark. Stopping after the first link leaves marks unclaimed even though nothing you wrote was actually wrong.

Worked example. "Explain why a satellite in a stable orbit continuously changes direction but not speed."
Incomplete answer: "Gravity acts on the satellite."
Complete answer: Gravity provides a centripetal force acting towards the centre of the orbit. This force is unbalanced, so it causes acceleration towards the centre. That acceleration changes the direction of the satellite's velocity, but because the force always acts at right angles to the direction of motion, it does not change the satellite's speed.

Notice how each sentence in the complete answer adds a new, necessary link rather than restating the previous one in different words. That's the structure examiners are looking for.

Forces and Their Interactions: A Second Common Trap

The wrong approach: describing only one half of an interaction pair, for example stating "the table pushes up on the book" without any mention of the matching force the book exerts on the table.

Why it loses marks: Newton's Third Law questions specifically test whether you understand that interaction forces come in pairs acting on two different objects, equal in magnitude and opposite in direction. Describing only one force in the pair, or describing two forces acting on the same object, misses the point of the question entirely.

Worked example. "A book rests on a table. Identify the Newton's Third Law pair to the force of the table pushing up on the book."
Wrong answer: "The weight of the book pulling it down." This is a different force acting on the same object, not a Third Law pair.
Correct answer: "The book pushing down on the table, with equal magnitude and opposite direction to the table's force on the book." This names the matching force, acting on the other object in the pair.

A quick check that catches this error every time: a genuine Newton's Third Law pair always involves the same two objects, with the forces swapped, and always acts on two different objects, never both on the same one.

Timing Failures

The wrong approach: spending disproportionate time on early, lower-mark questions, leaving insufficient time for the longer extended-response questions near the end of the paper.

Why it loses marks: marks are marks regardless of where they sit on the paper, but a 6-mark extended-response question left blank due to running out of time is a far bigger loss than the one or two marks you might have squeezed from over-polishing an earlier 2-mark question.

The correct technique: use a rough mark-a-minute pace as a running check throughout the paper, and if a question is taking noticeably longer than its marks justify, flag it and move on. Come back at the end if time allows. Never let a single stubborn question consume time that belongs to questions you haven't attempted yet.

Topic-Specific Misconceptions

Some errors aren't about exam technique at all, they're genuine misunderstandings of the physics, and they tend to recur in the same topics year after year.

Topic	Common misconception	Correct understanding
Electrical Circuits	Current is "used up" as it flows around a series circuit	Current is the same at every point in a series circuit; it's energy, not current, that's transferred to components
Energy Transfers, Conservation and Dissipation of Energy	Energy is "lost" when it's dissipated	Energy is conserved; dissipated energy is transferred to the surroundings, usually as heat, and becomes less useful, but it hasn't disappeared
Motion	A constant speed means zero force is acting	A constant velocity means zero resultant force; if the object is changing direction at constant speed, a resultant force is still acting
Energy Transfers and Particle Motion	Convection happens in solids as well as fluids	Convection depends on particles being free to move and carry energy with them, so it only occurs in fluids (liquids and gases), not solids
Forces and Their Interactions	A heavier object falls faster than a lighter one in the absence of air resistance	In the absence of air resistance, all objects accelerate at the same rate under gravity regardless of mass; it's air resistance that makes the difference in practice

Each of these misconceptions tends to feel intuitively correct, which is exactly why it persists. The fix isn't just memorising the correct statement; it's understanding the reasoning that makes the intuitive version wrong, so you can reconstruct the correct answer even when a question phrases it in an unfamiliar way.

Motion: Confusing Distance-Time and Velocity-Time Graphs

The wrong approach: reading a velocity-time graph as if it behaved like a distance-time graph, in particular treating a horizontal line on a velocity-time graph as meaning "not moving" rather than "moving at constant velocity."

Why it loses marks: the two graph types encode completely different information from the same underlying motion, and mixing up their conventions produces answers that are internally inconsistent even when the arithmetic is otherwise correct.

Graph type	Gradient represents	Area under graph represents
Distance-time	Speed	Not meaningful
Velocity-time	Acceleration	Distance travelled

The correct technique: before reading any value off a motion graph, check the label on the vertical axis. A flat line on a distance-time graph means stationary; a flat line on a velocity-time graph means constant velocity, and specifically zero acceleration, which is a very different statement. Confusing the two is one of the fastest ways to lose marks on an otherwise straightforward graph question.

A Worked Comparison: Energy Dissipation

Question: A motor is 60% efficient. Explain what happens to the remaining 40% of the input energy.
Weak answer: "40% of the energy is lost."
Strong answer: "40% of the input energy is not usefully transferred into kinetic energy. Instead, it is dissipated, mainly as heat due to friction in the motor's moving parts and resistance in its wiring, and transferred to the surroundings. The total energy is still conserved; it has simply been transferred in a less useful form rather than destroyed."

The strong answer avoids the word "lost" entirely, because energy conservation is a core principle the specification expects you to apply consistently, and using loose language around it is one of the fastest ways to suggest a misconception that isn't actually there.

Self-Check Questions

Explain the difference in what's expected between a "describe" answer and an "explain" answer.
Why does showing your working in a calculation matter even when you're confident in the final answer?
A ball is dropped and a second, heavier ball is dropped from the same height at the same time, with air resistance ignored. Which lands first, and why?
Explain why convection cannot take place in a solid.
Explain what happens to the energy in a device that is not 100% efficient, without using the word "lost."

None of these mistakes are difficult to fix once you can see the pattern behind them. Misread command words, unshown working, incomplete chains of reasoning, poor time management and a small set of recurring misconceptions account for the overwhelming majority of marks lost by otherwise well-prepared candidates. Work through these exam tips alongside real past-paper questions, checking every answer against the mark scheme's exact wording, and you'll start to recognise these patterns in your own work before they cost you marks on the day. Revisit these oxfordaqa igcse physics exam tips the week before your exam, alongside a fresh set of past-paper questions, and check whether any of these five patterns still show up in your own answers.