DSE Revision and Exam Preparation
FoundationDSE Physics has Paper 1 compulsory (60%, 2.5 h) and Paper 2 electives, two of four (20%, 1 h), plus SBA at 20%; mastering MC pacing, the long-question answering framework and the classic traps of the five topic areas secures the grade.
- The exam: Paper 1 compulsory 60% (2.5 h), Paper 2 electives two-of-four 20% (1 h), SBA 20%; standards-referenced Levels 1–5 with 5** at the top
- MC pacing: easy first, cover the options and predict, then eliminate; about a minute per item, skipping hard ones decisively
- Long questions mark by step: principle, formula, substitution, answer with units — all four; explanations in cause-and-effect physics language
文體小知識：科學知識說明文——拆解 DSE 物理考評結構與各卷題型，盤點五大課題易錯位，提供實戰應試策略。
§Text Passage
1Know the exam before fighting it. The DSE Physics public examination has two papers: Paper 1 covers all compulsory content at 60% of the total with 2.5 hours, mixing multiple-choice, short and structured long questions; Paper 2 carries 20% in 1 hour, answering any two of four elective topics — Astronomy and Space Science, Atomic World, Energy and Use of Energy, and Medical Physics; School-based Assessment takes the remaining 20%, assessing practical work across S5 and S6. Results are standards-referenced from Level 1 to 5, with 5** for the very best.
2Multiple-choice questions span the whole syllabus and time is tight — roughly a minute or so per item. The strategy: easy ones first, keep the pace. Circle the key words, cover the options and think of your own answer, then eliminate the obviously wrong choices one by one; in circuit questions mark current directions and meter readings on the figure, in mechanics draw the free-body diagram first. Skip stubborn items decisively and return later — never let one question drain the time of the whole paper.
3Long questions award marks step by step, so answer within a framework: state the principle or law, write the formula, substitute the numbers, and always finish with units. For explanations use cause-and-effect phrasing — 'because the magnetic flux is unchanged, no e.m.f. is induced in the secondary' — not just 'd.c. does not work'. Keep the layout clear and the wording lean so examiners see every scoring point; give answers to two or three significant figures and double-check unit conversions.
4When revising the five topic areas, audit the classic traps one by one. Mechanics: centripetal force is not an extra force, and satellite distances are measured from the Earth's centre. Electricity: series adds directly and parallel adds reciprocals, converting kilowatt-hours to joules means multiplying by 3.6 million, and fuses must sit in the live wire. These are the perennial marks-drainers; in the final ten days redo one matching question per trap — repeating an old mistake is the costliest error, and your mistake notebook is your most valuable private library.
5Run through electromagnetism and radioactivity traps too: left hand for motion, right hand for electricity; transformers work only on a.c.; high-voltage transmission cuts the cable loss; penetrating power and ionizing power of the three radiations are inversely related; count half-lives first, then halve step by step; background radiation is mostly natural. In the final fortnight, practise by question type against the clock with past papers — one specialism a day — clearing your mistake notebook topic by topic, and exam-day rhythm will take care of itself.
1Summary 重點摘要
DSE Physics has Paper 1 compulsory (60%, 2.5 h) and Paper 2 electives, two of four (20%, 1 h), plus SBA at 20%; mastering MC pacing, the long-question answering framework and the classic traps of the five topic areas secures the grade.
2Vocabulary cards Vocabulary
The content every candidate must study, examined in Paper 1 at 60% of the total over 2.5 hours.
The part examined by choosing any two of the four elective units, Paper 2 at 20% in 1 hour.
Objective items with four options; numerous and time-pressured, they reward speed with accuracy.
Long questions broken into parts, marked step by step, balancing calculation and explanation.
Assessment administered by schools on practical work across S5 and S6, worth 20% of the total.
The reporting system that matches performance against defined standards, Levels 1 to 5, with 5** for the very best.
The share of the total mark carried by each paper or topic; use weightings to prioritise revision time.
The official guide listing scoring points per step; use it to audit your own answering format during revision.
Planning time per section by question count and marks: easy items first, with time reserved to check.
The recurring errors of past candidates — missing units, series/parallel mix-ups, half-life slips; organise your mistake notebook around them.
3Step by step Steps
- Step 1: The assessment structure at a glanceThe DSE Physics grade is built from three parts: Paper 1 compulsory, 60% over 2.5 hours, covering the five compulsory areas — heat and gases, force and motion, wave motion, electricity and magnetism, and radioactivity and nuclear energy — with multiple-choice and structured long questions; Paper 2 electives, 20% in 1 hour, any two of four units; and school-based assessment at 20%. For example, if you aim at Level 5, mechanics and electricity in Paper 1 must be secured, as they carry the most questions. Results report standards-referenced Levels 1–5, with 5** at the top.
- Step 2: Pacing the multiple-choice sectionMC questions cover everything and time is tight — about a minute or so each. The method: a fast first pass answering what you know, circling and skipping the hard ones; a second pass attacking the circles; and an elimination sweep for the stragglers. For example, on a tangled circuit question, mark the current directions and the known voltmeter reading on the figure first, then apply Ohm's law section by section — often two steps reveal the answer; covering the options and predicting first stops plausible distractors from steering you. Never spend more than two minutes on one item.
- Step 3: The long-question frameworkLong questions mark step by step; the standard frame is principle, formula, substitution, answer with units — all four. Explanation answers need cause-and-effect phrasing in physics language. For example, asked why a transformer cannot use d.c., the full-mark line is 'the magnetic flux from a direct current does not change with time, so no e.m.f. is induced in the secondary' — flux as the cause, induced e.m.f. as the effect; 'it just cannot use d.c.' earns little or nothing. Give two to three significant figures and check units; answer part by part so examiners find every point.
- Step 4: Mechanics and heat trapsThe mechanics trap list: centripetal force is not an extra force, so never add an extra arrow to the free-body diagram; in satellite problems r is the distance from the Earth's centre; resolve weight on slopes before anything else; mind the signs of direction in momentum conservation. For example, in the minimum-speed-at-the-top question, the key sentence is the limiting condition 'normal force equals zero' — omit it and the explanation marks vanish. In heat, never mix specific heat capacity with latent heat; temperature stays constant during a change of state. These traps return yearly with new clothing; redoing the matching questions beats doing ten new ones.
- Step 5: Electricity and electromagnetism trapsElectricity traps: series adds directly, parallel adds reciprocals; 1 degree = 3.6 × 10⁶ J; fuse and switch belong in the live wire; choose among the three power formulas by what is known. Electromagnetism traps: left hand for motors, right hand for generators; transformers work only on a.c.; the 'opposing the change' direction in Lenz's law; and in transmission-loss calculations use the cable current, not the transmission voltage. For example, given the transmission voltage and cable resistance, first find the cable current from P = VI, then the loss from I²R — plugging in the wrong voltage sinks the whole question, so drill it until safe.
- Step 6: Waves and radioactivity trapsWave traps: in v = fλ the frequency is set by the source and does not change entering a new medium — speed and wavelength change together; total internal reflection needs dense-to-less-dense plus an angle beyond the critical angle. Radioactivity traps: penetrating and ionizing powers of the three radiations are inversely related; count half-lives first, then halve; balance both rows of a nuclear equation; background radiation is mostly natural. For example, light passing from air into water keeps its frequency while speed and wavelength shrink together to about three-quarters — write the full sentence rather than a bare formula for a safer mark.
- Step 7: A revision plan and exam-day mindsetSix weeks out, work in three phases: first, one pass over every topic guided by your mistake notebook and formula list; second, past-paper questions by type, one specialism a day against the clock; third, two or three full timed mocks. For example, in your electromagnetism week: Monday field-rule diagrams, Tuesday transformer calculations, Wednesday transmission long questions — clearing each day. On exam day: skim the whole paper for a minute, breathe, allocate time by the weightings; on an unfamiliar question, return to definitions and basic formulas — most of the marks can still be dismantled.
4Diagrams Diagrams
5Worked example Example
Example (a typical long question, dissected): a 1000 kg satellite orbits the Earth in a circle of radius 7.0 × 10⁶ m. Taking G = 6.67 × 10⁻¹¹ N m² kg⁻² and the Earth's mass M = 6.0 × 10²⁴ kg, find (a) the orbital speed; (b) the period; (c) explain why the satellite does not fall to the ground.
- Read and set up: gravity supplies the centripetal force, GMm/r² = mv²/r
- Part (a): v = √(GM/r) = √(6.67 × 10⁻¹¹ × 6.0 × 10²⁴ ÷ 7.0 × 10⁶) = √(5.7 × 10⁷) ≈ 7.6 × 10³ m s⁻¹
- Part (b): T = 2πr ÷ v = 2π × 7.0 × 10⁶ ÷ 7.6 × 10³ ≈ 5.8 × 10³ s, about 97 minutes
- Part (c): gravity keeps pulling the satellite towards the Earth (centripetal acceleration), but its large tangential speed means it keeps 'falling' while the curved surface falls away beneath it, so it holds a stable orbit and never lands
- Answer: (a) v = √(GM/r) ≈ 7.6 × 10³ m s⁻¹. (b) T = 2πr/v ≈ 5.8 × 10³ s (about 97 minutes). (c) Gravity acts as the centripetal force, accelerating the satellite towards the centre, while its tangential speed keeps it circling — together they give a stable orbit. The lesson: for every part write the principle and formula, substitute with units, and give cause-and-effect in explanations — the full-mark format for long questions.
6Common mistakes Mistakes
7Quick check Quick check
Q1What weighting does DSE Physics Paper 1 carry, and how long is it?
Q2What does Paper 2 examine, and how do candidates choose?
Q3What is the weighting of school-based assessment, and what does it assess?
Q4What is the standard answering framework for calculation questions?
Q5Order the three radiations by penetrating power from weakest to strongest, with the stopping material for each.
8Recap Recap
- The exam: Paper 1 compulsory 60% (2.5 h), Paper 2 electives two-of-four 20% (1 h), SBA 20%; standards-referenced Levels 1–5 with 5** at the top
- MC pacing: easy first, cover the options and predict, then eliminate; about a minute per item, skipping hard ones decisively
- Long questions mark by step: principle, formula, substitution, answer with units — all four; explanations in cause-and-effect physics language
- Each topic has its traps: centripetal force source and centre-of-Earth distance, series/parallel and kWh conversion, left/right-hand rules and transformers, half-life counting and the radiation comparison table
- Revise in three phases: topic sweep → timed practice by question type → full mocks; the mistake notebook is your most cost-effective weapon