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Singapore Physics Olympiad (SPhO) — Parent & Student Guide

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05 Sep 2025, 00:00 Z

TL;DR
SPhO rewards deep conceptual fluency in mechanics, E&M and thermal/modern topics, plus disciplined practical skills. Build a June→November plan that blends past papers, experiment design, and error analysis. Distinctions open doors to APhO/IPhO training and strengthen H2/H3 Physics outcomes.

1 What is SPhO?

  • Organiser: Institute of Physics, Singapore (IPS)
  • Format: 4‑h Theory + 4‑h Practical (on separate days)
  • Typical cadence: November sittings; awards/ceremony thereafter
  • Eligibility: JC/IP candidates via school nomination (confirm yearly details)

2 Why SPhO matters for IP students

  • Curriculum bridge: accelerates H2 mastery; primes H3 research modules
  • Portfolio signalling: nationally recognised achievement; pipeline to APhO/IPhO
  • Metacognition: planning experiments under time pressure mirrors A‑Level Paper 3/4 skills

3 Paper structure and scoring

  • Theory: long structured problems; vector fluency, calculus in context
  • Practical: measurement, uncertainty propagation, calibration, graphing
  • Marking emphasis: physical reasoning, clear assumptions, units & sig‑fig discipline

Theory question patterns (illustrative)

  • Multi‑stage mechanics: modelling with free‑body diagrams → differential equation → limiting behaviour.
  • Circuits with non‑idealities: internal resistance, non‑ohmic elements, measurement loading.
  • Fields and induction: flux reasoning, Faraday/Lenz in time‑varying scenarios, energy transfer routes.
  • Thermal/modern: ideal‑gas modelling limits, kinetic‑theory estimates, simple decay chains.

4 Core topics and prep priorities

  • Mechanics: dynamics, energy, oscillations; multi‑step modeling
  • E&M: fields, circuits, induction; idealisations vs real components
  • Thermal/Modern: kinetic theory, thermodynamic cycles, basic atomic/nuclear models
  • Mathematical methods: series approximations, dimensional analysis

Deep‑dive habits

  • Always start with a diagram and variable definitions; track direction conventions.
  • Non‑idealities first: identify where real instruments/components alter the model.
  • Consistency checks: dimensional analysis, limiting cases, orders of magnitude.

5 Timeline: June → November (example cadence)

  • June–July: concept consolidation + targeted past Qs
  • Aug–Sep: mixed papers under time; lab technique refreshers
  • Oct: full‑dress simulations; practical rehearsal with uncertainty focus
  • Nov: taper, error‑log review, rest rhythm

Weekly cadence (example)

  • 1 theory set (2–3 long Qs) under timer + 1 lab rehearsal (60–90 min).
  • Maintain an error log with causes categorised as “concept”, “setup”, “algebra”, “units/rounding”.
  • Every second week: one full practical simulation with neat tables and graphs.

6 Practical skills and lab discipline

  • Planning: variables, controls, safe ranges; neat tabulation
  • Execution: repeated measurements, residual checks, outlier handling
  • Analysis: linearisation, gradient/area physics, uncertainty chains

Worked example (outline): Internal resistance of a cell

  1. Model: V = ε − Ir, with ε EMF and r internal resistance.
  2. Plan: vary R_load, measure (I, V), keep temperature constant.
  3. Plot: V vs I; best‑fit line slope = −r, intercept = ε.
  4. Uncertainty: use partial gradients Δr from extreme‑fit lines; report r ± Δr with units.
  5. Checks: power balance P_internal = I²r; verify with typical values.

Common practical pitfalls

  • Under‑specifying control variables and safe ranges.
  • Disordered tables: mix of units, inconsistent significant figures.
  • Graphs without labelled axes/units or with poor scale choice.

7 Bridges and next steps

  • SJPO → SPhO → APhO/IPhO pathway overview
  • Decide between extended Olympiad track vs syllabus‑first focus

Useful internal links

8 Resources and internal links

Note: IPS releases yearly details on format and eligibility via schools. Treat examples above as orientation; your school circular is authoritative for your cohort.

9 Worked examples (with solutions)

9.1 Induction and energy consistency (classic “loop entering B‑field”)

Problem. A conducting rectangular loop of width w and total resistance R is pulled at constant speed v into a region of uniform magnetic field B pointing into the page. The field edge is sharp and vertical. When a length x of the loop is inside the field, find (i) the induced emf, (ii) current, and (iii) the pulling force F required to keep speed constant. Show that the mechanical power input equals the electrical power dissipated.

Solution. Flux Φ = B·(w·x). The flux changes because x increases at rate v.

  1. Faraday: emf magnitude ε = |dΦ/dt| = B w v. Direction by Lenz: current opposes entry.
  2. Ohm’s law: I = ε / R = (B w v)/R.
  3. Magnetic force on the “leading” segment (length w) in field: F = I w B = (B w v / R)·w·B = B² w² v / R, opposing motion. To keep v constant, the applied pull must match this magnitude.

Power balance. Mechanical input P_mech = F v = (B² w² v / R)·v = B² w² v² / R. Electrical dissipation P_elec = I² R = (B² w² v²)/R. Hence P_mech = P_elec as expected (energy conservation). ∎

Exam habits. Draw a clear diagram, mark the “active” segment in field, and state Lenz’s direction verbally to avoid sign confusion.

9.2 Mechanics — two‑block system with friction

Problem. A block (mass m) rests on a rough horizontal table (coefficient of kinetic friction μ) and is connected by a light, inextensible string over a smooth pulley at the table’s edge to a hanging mass M. The system is released from rest and moves with acceleration a. Find a and the string tension T, assuming motion occurs and friction is kinetic.

Solution. Take rightward motion of m and downward motion of M as positive. For block m: friction f_k = μ m g opposes motion (leftward). Newton’s second law:

Table block: T − μ m g = m a.
Hanging block: M g − T = M a.
Add equations: (T − μ m g) + (M g − T) = (m + M) a ⇒ a = (M g − μ m g)/(m + M).

Back‑substitute to get T, e.g. from table block: T = m a + μ m g = m (M g − μ m g)/(m + M) + μ m g = (m M g + μ m² g + μ m g (m + M) − μ m² g)/(m + M) simplifies to T = (m M g + μ m M g)/(m + M) = m M g (1 + μ)/(m + M).

Sanity checks.
• If μ = 0, a = M g/(m + M) (frictionless Atwood variant).
• If M ≪ μ m, acceleration tends to negative (no motion); consistent with the “assuming motion” clause—use inequality M > μ m to ensure sliding.

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