List

IPhO Problems and Solutions

The oldest and best known of the physics olympiads, first held in Warsaw in 1967. Each country sends up to five students for a theoretical and an experimental exam. Many older exams contain errors, catalogued in Stefan Ivanov's errata list.

2026 materialsTheory instructions

2026

Colombia

Theory3 problems
Experimental1 problemIdeal Gas, Vapor Pressure, and Heat ConductionProblemSolution
  • 4ExperimentalIdeal Gas, Vapor Pressure, and Heat ConductionProblemSolution

Theory3 problems
Experimental2 problems
  • 4ExperimentalEarth's magnetic field measurementProblemSolution
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  • 5ExperimentalSand craters and dunesProblemSolution
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Theory Backup1 problemStrongly correlated Fermi gasesProblem
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  • 6Theory BackupStrongly correlated Fermi gasesProblem
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2024 materialsMinutes

2024

Iran

Theory3 problems
Experimental2 problems

Theory3 problems
Experimental2 problems

Theory3 problems
Experimental2 problems

Theory3 problems
Experimental2 problems

2020

IdPhO

Theory3 problems
  • 1TheoryProblem MixProblemSolution
  • 2TheoryAnisotropic FrictionProblemSolution
  • 3TheoryLaser TechnologiesProblemSolution
Experimental1 problemCrystallographyProblemSolution

2019 materialsMinutes

2019

Israel

Theory3 problems
Experimental2 problems

2018 materialsMinutes

2018

Portugal

Theory3 problems
Experimental2 problems

Theory3 problems
Experimental2 problems
  • 4ExperimentalOptics of a Salt SolutionProblemSolution
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  • 5ExperimentalEarthquake and Volcano SensingProblemSolution
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Theory3 problems
Experimental2 problems

2015 materialsResultsMinutes

2015

India

Theory3 problems
  • 1TheoryParticles from the SunProblemSolution
  • 2TheoryThe Extremum PrincipleProblemSolution
  • 3TheoryThe Design of a Nuclear ReactorProblemSolution
Experimental2 problems
  • 4ExperimentalDiffraction due to Helical StructureProblemSolution
  • 5ExperimentalDiffraction due to Surface TensionProblemSolution

2014 materialsMinutes

2014

Kazakhstan

Theory3 problems
Experimental1 problemTo see invisible!ProblemSolution
  • 4ExperimentalTo see invisible!ProblemSolution

2013

Denmark

Theory3 problems
  • 1TheoryThe Maribo MeteoriteProblemSolution
  • 2TheoryPlasmonic Steam GeneratorProblemSolution
  • 3TheoryThe Greenlandic Ice SheetProblemSolution
Experimental2 problems
  • 4ExperimentalSpeed of LightProblemSolution
  • 5ExperimentalSolar CellsProblemSolution

2012

Estonia

Theory3 problems
  • 1TheoryFocus on sketchesProblemSolution
  • 2TheoryKelvin water dropperProblemSolution
  • 3TheoryProtostar formationProblemSolution
Experimental2 problems
  • 4ExperimentalThe Magnetic Permeability of WaterProblemSolution
  • 5ExperimentalNonlinear Black BoxProblemSolution

2011 materialsMinutes

2011

Thailand

Theory3 problems
  • 1TheoryA Three-body Problem and LISAProblemSolution
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  • 2TheoryAn Electrified Soap BubbleProblemSolution
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  • 3TheoryScattering of an Ion by a Neutral AtomProblemSolution
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Experimental2 problems
  • 4ExperimentalBlackbox: Capacitive Displacement SensorProblemSolution
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  • 5ExperimentalMechanical Blackbox: a cylinder with a ball insideProblemSolution
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Theory3 problems
Experimental2 problems

2009 materialsMinutes

2009

Mexico

Theory3 problems
  • 1TheoryEvolution of the Earth-Moon SystemProblemSolution
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  • 2TheoryDoppler Laser Cooling and Optical MolassesProblemSolution
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  • 3TheoryWhy are Stars so Large?ProblemSolution
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Experimental2 problems
  • 4ExperimentalWavelength of a Diode LaserProblemSolution
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  • 5ExperimentalBirefringence of MicaProblemSolution
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2008 materialsMinutes

2008

Vietnam

Theory3 problems
  • 1TheoryWater-Powered Rice-Pounding MortarProblemSolution
  • 2TheoryCherenkov Light and Ring Imaging CounterProblemSolution
  • 3TheoryChange of Air Temperature in the AtmosphereProblemSolution
Experimental1 problemDifferential Thermometric MethodProblemSolution
  • 4ExperimentalDifferential Thermometric MethodProblemSolution


2006 materialsMinutes

2006

Singapore

Theory3 problems
  • 1TheoryGravity in a Neutron InterferometerProblemSolution
  • 2TheoryWatching a Rod in MotionProblemSolution
  • 3TheoryFive EstimationsProblemSolution
Experimental1 problemInterference, Reflection and DiffractionProblemSolution
  • 4ExperimentalInterference, Reflection and DiffractionProblemSolution

2005 materialsMinutes

2005

Spain

Theory3 problems
  • 1TheoryAn ill Fated SatelliteProblemSolution
  • 2TheoryAbsolute Measurements of Electrical QuantitiesProblemSolution
  • 3TheoryNeutrons in a Gravitational FieldProblemSolution
Experimental1 problemPlanck's Constant in an Incandescent LampProblemSolution
  • 4ExperimentalPlanck's Constant in an Incandescent LampProblemSolution

2004 materialsMinutes

2004

Korea

Theory3 problems
Experimental1 problemMechanical "Black Box"ProblemSolution
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2003 materialsMinutes

2003

Taiwan

Theory3 problems
  • 1TheoryA Swing with a Falling WeightProblemSolution
  • 2TheoryA Piezoelectric Crystal ResonatorProblemSolution
  • 3TheoryNeutrino Mass and Neutron DecayProblemSolution
Experimental1 problemOptical Properties of Laser DiodeProblemSolution
  • 4ExperimentalOptical Properties of Laser DiodeProblemSolution

Theory3 problems
  • 1TheoryGround-Penetrating RadarProblemSolution
  • 2TheorySensing Electrical SignalsProblemSolution
  • 3TheoryA Heavy Vehicle Moving on An Inclined RoadProblemSolution
Experimental2 problems
  • 4ExperimentalPhysical Constants with ElectrolysisProblemSolution
  • 5ExperimentalOptical Black BoxProblemSolution

2001 materialsMinutes

2001

Turkey

Theory3 problems
  • 1TheoryFour ProblemsProblemSolution
  • 2TheoryBinary Star SystemProblemSolution
  • 3TheoryMagnetohydrodynamic (MHD) GeneratorProblemSolution
Experimental1 problemRotating LiquidProblemSolution
  • 4ExperimentalRotating LiquidProblemSolution

2000 materialsMinutes

2000

United Kingdom

Theory3 problems
  • 1TheoryFive ProblemsProblemSolution
  • 2TheoryCathode Ray TubeProblemSolution
  • 3TheoryGravitational Waves and LightProblemSolution
Experimental2 problems
  • 4ExperimentalCDROM SpectrometerProblem
  • 5ExperimentalThe Magnetic PuckProblem

1999 materialsMinutes

1999

Italy

Theory3 problems
  • 1TheoryAbsorption of Radiation by a GasProblemSolution
  • 2TheoryMagnetic field with a V-shaped wireProblemSolution
  • 3TheoryA Space Probe to JupiterProblemSolution
Experimental1 problemTorsion pendulumProblemSolution
  • 4ExperimentalTorsion pendulumProblemSolution

1998 materialsMinutes

1998

Iceland

Theory3 problems
  • 1TheoryRolling of a Hexagonal PrismProblemSolution
  • 2TheoryWater under an Ice CapProblemSolution
  • 3TheoryFaster than Light?ProblemSolution
Experimental1 problemElectromagnetismProblem
  • 4ExperimentalElectromagnetismProblem

1997

Canada

Theory3 problems
  • 1TheoryScalingsProblemSolution
  • 2TheoryNuclear Masses and StabilityProblemSolution
  • 3TheorySolar-Powered AircraftProblemSolution
Experimental1 problemCharacterization of the BimorphProblemSolution
  • 4ExperimentalCharacterization of the BimorphProblemSolution

1996

Norway

Theory3 problems
  • 1TheoryFive ProblemsProblemSolution
  • 2TheoryDynamics of Electrons and CylindersProblemSolution
  • 3TheoryMoon and TidesProblemSolution
Experimental1 problemGravity and MagnetismProblemSolution
  • 4ExperimentalGravity and MagnetismProblemSolution

1995 materialsComments

1995

Australia

Theory3 problems
  • 1TheoryGravitational Red Shift and Stellar MassProblemSolution
  • 2TheorySound PropagationProblemSolution
  • 3TheoryCylindrical BuoyProblemSolution
Experimental2 problems
  • 4ExperimentalTerminal Velocity in a Viscous LiquidProblemSolution
  • 5ExperimentalDiffraction and Scattering of Laser LightProblemSolution

1994

China

Theory3 problems
  • 1TheoryRelativistic ParticleProblemSolution
  • 2TheorySuperconducting MagnetProblemSolution
  • 3TheoryCollision of Discs with Surface FrictionProblemSolution
Experimental2 problems
  • 4ExperimentalLight Reflectivity of a Transparent DielectricProblemSolution
  • 5ExperimentalTwo Terminal Black BoxProblemSolution

1993

USA

Theory3 problems
  • 1TheoryAtmospheric ElectricityProblemSolution
  • 2TheoryLaser Forces on a Transparent PrismProblemSolution
  • 3TheoryElectron BeamProblemSolution
Experimental2 problems
  • 4ExperimentalHeat of Vaporization of NitrogenProblemSolution
  • 5ExperimentalMagnetic Moments and FieldsProblemSolution

1992

Finland

Theory3 problems
  • 1TheoryA Rotating SatelliteProblemSolution
  • 2TheoryThe Longitudinal Motion of a Linear MoleculeProblemSolution
  • 3TheoryA Satellite in SunshineProblemSolution
Experimental2 problems
  • 4ExperimentalElectric Breakdown of AirProblemSolution
  • 5ExperimentalA Grating and Optical FiltersProblemSolution

1991

Cuba

Theory3 problems
  • 1TheoryFriction on ImpactProblemSolution
  • 2TheoryRelativistic SquareProblemSolution
  • 3TheoryCooling Atoms by LaserProblemSolution
Experimental1 problemThree Terminal Black BoxProblemSolution
  • 4ExperimentalThree Terminal Black BoxProblemSolution

1990

Netherlands

Theory3 problems
  • 1TheoryX-ray Diffraction from a CrystalProblemSolution
  • 2TheoryElectric Experiments in the MagnetosphereProblemSolution
  • 3TheoryThe Rotating Neutron StarProblemSolution
Experimental2 problems
  • 4ExperimentalLED EfficiencyProblemSolution
  • 5ExperimentalTwo MagnetsProblemSolution

1989

Poland

Theory3 problems
  • 1TheoryBoiling LiquidsProblemSolution
  • 2TheoryRotating MassesProblemSolution
  • 3TheoryProton MicroscopeProblemSolution
Experimental1 problemPiezoelectric DiscsProblemSolution
  • 4ExperimentalPiezoelectric DiscsProblemSolution

1988

Austria

Theory3 problems
  • 1TheorySpectroscopy of Particle VelocitiesProblemSolution
  • 2TheoryMaxwell's WheelProblemSolution
  • 3TheoryRecombination of Ions in Ionized GasProblemSolution
Experimental2 problems
  • 4ExperimentalPolarized LightProblemSolution
  • 5ExperimentalElectron TubeProblemSolution

1987

East Germany

Theory3 problems
  • 1TheoryAscending Moist AirProblemSolution
  • 2TheoryElectrons in a Magnetic FieldProblemSolution
  • 3TheoryInfinite LC-gridProblemSolution
Experimental1 problemRefractive IndicesProblemSolution
  • 4ExperimentalRefractive IndicesProblemSolution

1986

United Kingdom

Theory3 problems
  • 1TheoryWave InterferenceProblemSolution
  • 2TheorySeismic WavesProblemSolution
  • 3TheoryMasses and SpringsProblemSolution
Experimental2 problems
  • 4ExperimentalPendant DropProblemSolution
  • 5ExperimentalMicrocomputerProblemSolution

1985

Yugoslavia

Theory3 problems
Experimental2 problems
  • 4ExperimentalBrass DiskProblemSolution
  • 5ExperimentalPermanent MagnetsProblemSolution

1984

Sweden

Theory3 problems
Experimental2 problems
  • 4ExperimentalDiode, Capacitor and ResistorProblemSolution
  • 5ExperimentalGlow Discharge LampProblemSolution


1982

West Germany

Theory3 problems
  • 1TheoryFluorescent lampProblemSolution
  • 2TheoryOscillating coat hangerProblemSolution
  • 3TheoryHot-air-balloonProblemSolution
Experimental2 problems
  • 4ExperimentalLens ExperimentProblemSolution
  • 5ExperimentalMotion of a Rolling CylinderProblemSolution

1981

Bulgaria

Theory3 problems
  • 1TheoryGas Container RocketProblemSolution
  • 2TheoryElectric LampProblemSolution
  • 3TheoryDetecting Astronomical RadiowavesProblemSolution
Experimental1 problemElastic Rubber CordProblemSolution
  • 4ExperimentalElastic Rubber CordProblemSolution

1979

Soviet Union

Theory3 problems
  • 1TheoryTo the Moon!ProblemSolution
  • 2TheoryInfluence of Humidity on ScalesProblemSolution
  • 3TheoryReflectors on the MoonProblemSolution
Experimental1 problemBlack BoxProblemSolution
  • 4ExperimentalBlack BoxProblemSolution

1977

Czechoslovakia

Problems3 problems

1976

Hungary

Theory3 problems
  • 1TheorySpinning Block Inside a SphereProblemSolution
  • 2TheoryA Valve in a CylinderProblemSolution
  • 3TheoryAir Bubble inside a Glass SphereProblemSolution
Experimental1 problemThermal Properties of the X materialProblemSolution
  • 4ExperimentalThermal Properties of the X materialProblemSolution

1975

East Germany

Theory3 problems
  • 1TheoryRotating RodProblemSolution
  • 2TheoryThick LensProblemSolution
  • 3TheoryIons in a Magnetic FieldProblemSolution
Experimental1 problemSemiconductor ElementProblemSolution
  • 4ExperimentalSemiconductor ElementProblemSolution

1974

Poland

Theory3 problems
  • 1TheoryHydrogen Atoms CollidingProblemSolution
  • 2TheoryBending LightProblemSolution
  • 3TheorySurviving with ThermodynamicsProblemSolution
Experimental1 problemDiodes in a Black BoxProblemSolution
  • 4ExperimentalDiodes in a Black BoxProblemSolution

1972

Romania

Theory4 problems
  • 1TheoryThree CylindersProblemSolution
  • 2TheoryMolecular PhysicsProblemSolution
  • 3TheoryDielectric LiquidProblemSolution
  • 4TheoryGeometrical Optics and InterferenceProblemSolution
Experimental1 problemTwo CylindersProblemSolution
  • 5ExperimentalTwo CylindersProblemSolution

1971

Bulgaria

Theory4 problems
  • 1TheoryConnected Masses on a PrismProblemSolution
  • 2TheoryMercury BarometerProblemSolution
  • 3TheoryBatteries, Capacitors and Resistors in a CubeProblemSolution
  • 4TheorySpherical AquariumProblemSolution
Experimental1 problemRheostat DissipationProblemSolution
  • 5ExperimentalRheostat DissipationProblemSolution

1970

Soviet Union

Theory4 problems
  • 1TheoryCarrying a BarProblemSolution
  • 2TheoryA Chemistry Problem (Salt Crystals)ProblemSolution
  • 3TheorySpherical CapacitorsProblemSolution
  • 4TheoryA Telescope with a Spherical MirrorProblemSolution
Experimental1 problemThree LensesProblemSolution
  • 5ExperimentalThree LensesProblemSolution

1969

Czechoslovakia

Problems4 problems
  • 1Three CartsProblemSolution
  • 2Water inside a Copper CalorimeterProblemSolution
  • 3Suspended Charged BallProblemSolution
  • 4Glass Plate above a Glass CubeProblemSolution

1968

Hungary

Theory3 problems
  • 1TheoryBlock and Cylinder on an Inclined PlaneProblemSolution
  • 2TheoryMixing TolueneProblemSolution
  • 3TheoryGlass Semi-cylinderProblemSolution
Experimental1 problemThree Black BoxesProblemSolution
  • 4ExperimentalThree Black BoxesProblemSolution

1967

Poland

Theory4 problems
  • 1TheoryShooting a BallProblemSolution
  • 2TheoryInfinite Network of ResistorsProblemSolution
  • 3TheoryHeating BallsProblemSolution
  • 4TheoryHeating a VesselProblemSolution
Experimental1 problemHeating PetroleumProblemSolution
  • 5ExperimentalHeating PetroleumProblemSolution