APhO Problems and Solutions

2026 materialsResults

2026

South Korea

Theory3 problems

1TheoryPhysics of Weighing ScalesProblem Solution
2TheoryDiffraction of X-rays by Structured and Evolving TargetsProblem Solution
3TheoryMagnetic Resonance and External FluctuationProblem Solution

Experimental2 problems

4ExperimentalWater Clock ExperimentProblem Solution
5ExperimentalEstimation of Unknown ResistanceProblem Solution

2025 materialsResults

2025

Saudi Arabia

Theory3 problems

1TheoryPrecession of the Earth's axisProblem Solution
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2TheoryWaves and Phase Transitions in Spin SystemsProblem Solution
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3TheoryAtmospheric PhysicsProblem Solution
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Experimental1 problemPhysics of Induction CookingProblem Solution

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4ExperimentalPhysics of Induction CookingProblem Solution
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2024

Malaysia

Theory3 problems

1TheoryGeometry of Water FountainProblem Solution
2TheorySnell's LawProblem Solution
3TheoryThe First Discovered Quasar: Unveiling the Mysteries of the Astrophysical Source 3C 273Problem Solution

Experimental1 problemGyroscopeProblem Solution

4ExperimentalGyroscopeProblem Solution

2023 materialsExperiment instructions

2023

Mongolia

Theory3 problems

1TheoryISS Orbital Decay DynamicsProblem Solution
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2TheoryA ball on a turntableProblem Solution
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3TheoryCavitationProblem Solution
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Experimental2 problems

4ExperimentalHertzian Contact StressProblem Solution
5ExperimentalInterference from thermally deformed surface (thermos-deformation)Problem Solution

2022 materialsTheory instructions Experiment instructions Experimental Presentation Results

2022

India

Theory3 problems

1TheoryThe Stern-Gerlach ExperimentProblem Solution
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2TheoryA Mechanical Model for Phase TransitionsProblem Solution
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3TheoryMaxwell, Rayleigh and Mount EverestProblem Solution
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Experimental2 problems

4ExperimentalMagnetic Black BoxProblem Solution
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5ExperimentalAcoustic Black BoxProblem Solution
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2021 materialsExperiment instructions Experiment data (zip)

2021

Taiwan

Theory3 problems

1TheoryWater-Hammer EffectProblem Solution
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2TheoryRay tracingProblem Solution
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3TheoryMagnetic LevitationProblem Solution
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Experimental2 problems

4ExperimentalElasticity of CantileverProblem Solution
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5ExperimentalExploring the Spatial Structure of the Sample with Optical MethodsProblem Solution
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2019 materialsTheory instructions Experiment instructions Results Proceedings

2019

Australia

Theory3 problems

1TheoryRF Reflectometry of Single-Electron CircuitsProblem Solution
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2TheoryJets from AGNProblem Solution
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3TheoryTippe topProblem Solution
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Experimental2 problems

4ExperimentalStatic response of a magnetically active fluidProblem Solution
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5ExperimentalWave pulses in a magnetically active fluidProblem Solution
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2018

Vietnam

Theory3 problems

1TheoryOptical Trap of Neutral AtomsProblem Solution
2TheorySpace ElevatorProblem Solution
3TheoryThermoelectric EffectsProblem Solution

Experimental1 problemGiant Magnetoresistance (GMR)Problem Solution

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4ExperimentalGiant Magnetoresistance (GMR)Problem Solution
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2017 materialsMinutes

2017

Russia

Theory3 problems

1TheoryVortices in superfluidProblem Solution
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2TheoryEvolution of Supermassive Black Holes BinaryProblem Solution
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3TheorySpace DebrisProblem Solution
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Experimental1 problemPhotonic CrystalProblem Solution

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4ExperimentalPhotonic CrystalProblem Solution
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2016 materialsTheory instructions Minutes

2016

Hong Kong

Theory3 problems

1TheoryMechanics of a Deformable LatticeProblem Solution
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2TheoryThe Expanding UniverseProblem Solution
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3TheoryMagnetic Field Effects on SuperconductorsProblem Solution
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Experimental2 problems

4ExperimentalReflected Optical Diffraction Patterns from One-Dimensional StructuresProblem Solution
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5ExperimentalReflection Phase Shift of MetalProblem Solution
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2015 materialsMinutes

2015

China

Theory3 problems

1TheoryFractional Quantum Hall effect (FQHE)Problem Solution
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2TheoryHow are Aurora Ignited by the Solar Wind?Problem Solution
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3TheoryFabry-Perot (F-P) etalonProblem Solution
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Experimental1 problemThe Piezoelectric Effect and Its ApplicationsProblem Solution

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4ExperimentalThe Piezoelectric Effect and Its ApplicationsProblem Solution
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2014 materialsMinutes

2014

Singapore

Theory3 problems

1TheoryHadley CirculationProblem Solution
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2TheoryTwo-Slit Electron InterferenceProblem Solution
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3TheoryGravitational LensingProblem Solution
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Experimental1 problemSpeed of Ultrasonic Sound in SolutionProblem Solution

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4ExperimentalSpeed of Ultrasonic Sound in SolutionProblem Solution
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2013 materialsMinutes

2013

Indonesia

Theory3 problems

1TheoryConductors in Conducting LiquidProblem Solution
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2TheoryRelativistic Correction on GPS SatelliteProblem Solution
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3TheoryPhysics of SpinProblem Solution
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Experimental1 problemWind Power and Its MetrologiesProblem Solution

4ExperimentalWind Power and Its MetrologiesProblem Solution

2012 materialsMinutes

2012

India

Theory3 problems

1TheoryThe Drag on a Falling MagnetProblem Solution
2TheoryChandrasekhar LimitProblem Solution
3TheoryPancharatnam PhaseProblem Solution

Experimental2 problems

4ExperimentalFrictionProblem Solution
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5ExperimentalElectromagnetic InductionProblem Solution
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2011 materialsMinutes

2011

Israel

Theory3 problems

1TheoryThe Shockley-James ParadoxProblem Solution
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2TheoryCreaking DoorProblem Solution
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3TheoryBirthday BalloonProblem Solution
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Experimental2 problems

4ExperimentalLevitation of Conductors in an Oscillating Magnetic FieldProblem Solution
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5ExperimentalAn Optical "Black Box"Problem Solution
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2010 materialsMinutes

2010

Taiwan

Theory3 problems

1TheoryParticles and WavesProblem Solution
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2TheoryStrong Resistive ElectromagnetsProblem Solution
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3TheoryElectron and Gas Bubbles in LiquidsProblem Solution
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Experimental2 problems

4ExperimentalMagnetic Force ProbeProblem Solution
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5ExperimentalUnderstanding Semiconductor LasersProblem Solution
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2009 materialsExperiment Marking Scheme

2009

Thailand

Theory3 problems

1TheoryRolling CylindersProblem Solution
2TheoryA Self-excited Magnetic DynamoProblem Solution
3TheoryThe Leidenfrost PhenomenonProblem Solution

Experimental2 problems

4ExperimentalThe Earth's Horizontal Magnetic FieldProblem Solution
5ExperimentalOscillation of Water-Filled VesselProblem Solution

2008 materialsMinutes

2008

Mongolia

Theory3 problems

1TheoryTea Ceremony and Physics of BubblesProblem Solution
2TheoryIonic Crystal, Yukawa-type Potential and Pauli PrincipleProblem Solution
3TheoryHow does a superluminal object look like?Problem Solution

Experimental1 problemThe Physics of Sound WaveProblem

4ExperimentalThe Physics of Sound WaveProblem

2007 materialsMinutes

2007

China

Theory3 problems

1TheoryBack-and-Forth Rolling of a Liquid-Filled SphereProblem Solution
2TheoryOptical properties of an unusual materialProblem Solution
3TheorySpecific heat of free electron gas at constant volumeProblem Solution

Experimental2 problems

4ExperimentalUsing the Interference Method to Measure the Thermal Expansion Coefficient and Temperature Coefficient of Refractive Index of GlassProblem Solution
5ExperimentalMeasurement of Liquid Electric ConductivityProblem Solution

2006 materialsMinutes

2006

Kazakhstan

Theory3 problems

1TheoryLaser cooling of atomsProblem Solution
2TheoryOscillator damped by sliding frictionProblem Solution
3TheoryThree ProblemsProblem Solution

Experimental1 problemSpecific heat of aluminum and latent heat of evaporationProblem Solution

4ExperimentalSpecific heat of aluminum and latent heat of evaporationProblem Solution

2005 materialsMinutes

2005

Indonesia

Problems3 problems

1Spring Cylinder With Massive PistonProblem Solution
2Magnetic FocusingProblem Solution
3Light Deflection by a Moving MirrorProblem Solution

Experimental2 problemsProblems Solutions

4Determination of Shapes by Reflectionnot published
5Magnetic Braking on an Inclined Planenot published

2004 materialsMinutes

2004

Vietnam

Theory3 problems

1TheoryMeasure the mass in the weightless stateProblem Solution
2TheoryOptical fiberProblem Solution
3TheoryCompression and expansion of a two gases systemProblem Solution

Experimental2 problems

4ExperimentalHall Effect and Magnetoresistivity EffectProblem Solution
5ExperimentalBlack BoxProblem Solution

2003 materialsMinutes

2003

Thailand

Theory3 problems

1TheorySatellite's orbit transferProblem Solution
2TheoryOptical GyroscopeProblem Solution
3TheoryPlasma LensProblem Solution

Experimental2 problems

4ExperimentalDetermination of CapacitanceProblem Solution
5ExperimentalCylindrical BoreProblem Solution

2002 materialsMinutes

2002

Singapore

Theory3 problems

1TheoryVibrations of a Linear Crystal LatticeProblem Solution
2TheoryThe Rail GunProblem Solution
3TheoryWater FabricationProblem Solution

Experimental2 problems

4ExperimentalPart A: Measurement of Reflectance and Determination of Refractive IndexProblem
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5ExperimentalPart B: Frequency of Vibration of a Tuning ForkProblem Solution

2001 materialsMinutes

2001

Taiwan

Theory3 problems

1TheoryWhen will the Moon become a Synchronous Satellite?Problem Solution
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2TheoryMotion of an Electric Dipole in a Magnetic FieldProblem Solution
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3TheoryThermal Vibrations of Surface AtomsProblem Solution
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Experimental1 problemBasic Characteristics of Solar CellsProblem Solution

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4ExperimentalBasic Characteristics of Solar CellsProblem Solution
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2000 materialsMinutes

2000

Indonesia

Problems3 problems

1Eclipses of the Jupiter's SatelliteProblem Solution
2Detection of Alpha ParticlesProblem Solution
3Stewart-Tolman EffectProblem Solution

Experimental2 problemsProblems Solutions

4Determination of the Density of Oilnot published
5Determination of the Stefan-Boltzmann Constantnot published