APhO Problems and Solutions
The Asian regional olympiad, first held in Indonesia in 2000. Teams are eight students rather than the five IPhO allows, and the exams are widely considered harder than IPhO's.
All Mechanics Electromagnetism Thermodynamics Waves & Optics Modern & Quantum Relativity Astrophysics
Newest first Cards List
Kinematics Dynamics Rigid body Fluids Gravitation Statics Electrostatics Circuits Magnetostatics Induction Em waves Heat transfer Gas laws Kinetic theory Phase transitions Statistical mechanics Oscillations Wave propagation Interference Diffraction Geometrical optics Polarization Atomic Nuclear Solid state Quantum mechanics General relativity Stellar Orbital mechanics Cosmology Observational
2026
South Korea
Theory 3 problems
1 Theory Physics of Weighing Scales Problem Solution APhO 2026 Theory problem 1, Physics of Weighing Scales 2 Theory Diffraction of X-rays by Structured and Evolving Targets Problem Solution APhO 2026 Theory problem 2, Diffraction of X-rays by Structured and Evolving Targets 3 Theory Magnetic Resonance and External Fluctuation Problem Solution APhO 2026 Theory problem 3, Magnetic Resonance and External Fluctuation Experimental 2 problems
4 Experimental Water Clock Experiment Problem Solution APhO 2026 Experimental problem 4, Water Clock Experiment 5 Experimental Estimation of Unknown Resistance Problem Solution APhO 2026 Experimental problem 5, Estimation of Unknown Resistance
2025
Saudi Arabia
Theory 3 problems
1 Theory Precession of the Earth's axis Problem Solution APhO 2025 Theory problem 1, Precession of the Earth's axis 2 Theory Waves and Phase Transitions in Spin Systems Problem Solution APhO 2025 Theory problem 2, Waves and Phase Transitions in Spin Systems 3 Theory Atmospheric Physics Problem Solution APhO 2025 Theory problem 3, Atmospheric Physics 4 Experimental Physics of Induction Cooking Problem Solution APhO 2025 Experimental problem 4, Physics of Induction Cooking
2024
Malaysia
Theory 3 problems
1 Theory Geometry of Water Fountain Problem Solution APhO 2024 Theory problem 1, Geometry of Water Fountain 2 Theory Snell's Law Problem Solution APhO 2024 Theory problem 2, Snell's Law 3 Theory The First Discovered Quasar: Unveiling the Mysteries of the Astrophysical Source 3C 273 Problem Solution APhO 2024 Theory problem 3, The First Discovered Quasar: Unveiling the Mysteries of the Astrophysical Source 3C 273 4 Experimental Gyroscope Problem Solution APhO 2024 Experimental problem 4, Gyroscope
2023
Mongolia
Theory 3 problems
1 Theory ISS Orbital Decay Dynamics Problem Solution APhO 2023 Theory problem 1, ISS Orbital Decay Dynamics 2 Theory A ball on a turntable Problem Solution APhO 2023 Theory problem 2, A ball on a turntable 3 Theory Cavitation Problem Solution APhO 2023 Theory problem 3, Cavitation Experimental 2 problems
4 Experimental Hertzian Contact Stress Problem Solution APhO 2023 Experimental problem 4, Hertzian Contact Stress 5 Experimental Interference from thermally deformed surface (thermos-deformation) Problem Solution APhO 2023 Experimental problem 5, Interference from thermally deformed surface (thermos-deformation)
2022
India
Theory 3 problems
1 Theory The Stern-Gerlach Experiment Problem Solution APhO 2022 Theory problem 1, The Stern-Gerlach Experiment 2 Theory A Mechanical Model for Phase Transitions Problem Solution APhO 2022 Theory problem 2, A Mechanical Model for Phase Transitions 3 Theory Maxwell, Rayleigh and Mount Everest Problem Solution APhO 2022 Theory problem 3, Maxwell, Rayleigh and Mount Everest Experimental 2 problems
4 Experimental Magnetic Black Box Problem Solution APhO 2022 Experimental problem 4, Magnetic Black Box 5 Experimental Acoustic Black Box Problem Solution APhO 2022 Experimental problem 5, Acoustic Black Box
2021
Taiwan
Theory 3 problems
1 Theory Water-Hammer Effect Problem Solution APhO 2021 Theory problem 1, Water-Hammer Effect 2 Theory Ray tracing Problem Solution APhO 2021 Theory problem 2, Ray tracing 3 Theory Magnetic Levitation Problem Solution APhO 2021 Theory problem 3, Magnetic Levitation Experimental 2 problems
4 Experimental Elasticity of Cantilever Problem Solution APhO 2021 Experimental problem 4, Elasticity of Cantilever 5 Experimental Exploring the Spatial Structure of the Sample with Optical Methods Problem Solution APhO 2021 Experimental problem 5, Exploring the Spatial Structure of the Sample with Optical Methods
2019
Australia
Theory 3 problems
1 Theory RF Reflectometry of Single-Electron Circuits Problem Solution APhO 2019 Theory problem 1, RF Reflectometry of Single-Electron Circuits 2 Theory Jets from AGN Problem Solution APhO 2019 Theory problem 2, Jets from AGN 3 Theory Tippe top Problem Solution APhO 2019 Theory problem 3, Tippe top Experimental 2 problems
4 Experimental Static response of a magnetically active fluid Problem Solution APhO 2019 Experimental problem 4, Static response of a magnetically active fluid 5 Experimental Wave pulses in a magnetically active fluid Problem Solution APhO 2019 Experimental problem 5, Wave pulses in a magnetically active fluid
2018
Vietnam
Theory 3 problems
1 Theory Optical Trap of Neutral Atoms Problem Solution APhO 2018 Theory problem 1, Optical Trap of Neutral Atoms 2 Theory Space Elevator Problem Solution APhO 2018 Theory problem 2, Space Elevator 3 Theory Thermoelectric Effects Problem Solution APhO 2018 Theory problem 3, Thermoelectric Effects 4 Experimental Giant Magnetoresistance (GMR) Problem Solution APhO 2018 Experimental problem 4, Giant Magnetoresistance (GMR)
2017
Russia
Theory 3 problems
1 Theory Vortices in superfluid Problem Solution APhO 2017 Theory problem 1, Vortices in superfluid 2 Theory Evolution of Supermassive Black Holes Binary Problem Solution APhO 2017 Theory problem 2, Evolution of Supermassive Black Holes Binary 3 Theory Space Debris Problem Solution APhO 2017 Theory problem 3, Space Debris 4 Experimental Photonic Crystal Problem Solution APhO 2017 Experimental problem 4, Photonic Crystal
2016
Hong Kong
Theory 3 problems
1 Theory Mechanics of a Deformable Lattice Problem Solution APhO 2016 Theory problem 1, Mechanics of a Deformable Lattice 2 Theory The Expanding Universe Problem Solution APhO 2016 Theory problem 2, The Expanding Universe 3 Theory Magnetic Field Effects on Superconductors Problem Solution APhO 2016 Theory problem 3, Magnetic Field Effects on Superconductors Experimental 2 problems
4 Experimental Reflected Optical Diffraction Patterns from One-Dimensional Structures Problem Solution APhO 2016 Experimental problem 4, Reflected Optical Diffraction Patterns from One-Dimensional Structures 5 Experimental Reflection Phase Shift of Metal Problem Solution APhO 2016 Experimental problem 5, Reflection Phase Shift of Metal
2015
China
Theory 3 problems
1 Theory Fractional Quantum Hall effect (FQHE) Problem Solution APhO 2015 Theory problem 1, Fractional Quantum Hall effect (FQHE) 2 Theory How are Aurora Ignited by the Solar Wind? Problem Solution APhO 2015 Theory problem 2, How are Aurora Ignited by the Solar Wind? 3 Theory Fabry-Perot (F-P) etalon Problem Solution APhO 2015 Theory problem 3, Fabry-Perot (F-P) etalon Experimental 1 problem The Piezoelectric Effect and Its Applications Problem Solution 4 Experimental The Piezoelectric Effect and Its Applications Problem Solution APhO 2015 Experimental problem 4, The Piezoelectric Effect and Its Applications
2014
Singapore
Theory 3 problems
1 Theory Hadley Circulation Problem Solution APhO 2014 Theory problem 1, Hadley Circulation 2 Theory Two-Slit Electron Interference Problem Solution APhO 2014 Theory problem 2, Two-Slit Electron Interference 3 Theory Gravitational Lensing Problem Solution APhO 2014 Theory problem 3, Gravitational Lensing 4 Experimental Speed of Ultrasonic Sound in Solution Problem Solution APhO 2014 Experimental problem 4, Speed of Ultrasonic Sound in Solution
2013
Indonesia
Theory 3 problems
1 Theory Conductors in Conducting Liquid Problem Solution APhO 2013 Theory problem 1, Conductors in Conducting Liquid 2 Theory Relativistic Correction on GPS Satellite Problem Solution APhO 2013 Theory problem 2, Relativistic Correction on GPS Satellite 3 Theory Physics of Spin Problem Solution APhO 2013 Theory problem 3, Physics of Spin 4 Experimental Wind Power and Its Metrologies Problem Solution APhO 2013 Experimental problem 4, Wind Power and Its Metrologies
2012
India
Theory 3 problems
1 Theory The Drag on a Falling Magnet Problem Solution APhO 2012 Theory problem 1, The Drag on a Falling Magnet 2 Theory Chandrasekhar Limit Problem Solution APhO 2012 Theory problem 2, Chandrasekhar Limit 3 Theory Pancharatnam Phase Problem Solution APhO 2012 Theory problem 3, Pancharatnam Phase Experimental 2 problems
4 Experimental Friction Problem Solution APhO 2012 Experimental problem 4, Friction 5 Experimental Electromagnetic Induction Problem Solution APhO 2012 Experimental problem 5, Electromagnetic Induction
2011
Israel
Theory 3 problems
1 Theory The Shockley-James Paradox Problem Solution APhO 2011 Theory problem 1, The Shockley-James Paradox 2 Theory Creaking Door Problem Solution APhO 2011 Theory problem 2, Creaking Door 3 Theory Birthday Balloon Problem Solution APhO 2011 Theory problem 3, Birthday Balloon Experimental 2 problems
4 Experimental Levitation of Conductors in an Oscillating Magnetic Field Problem Solution APhO 2011 Experimental problem 4, Levitation of Conductors in an Oscillating Magnetic Field 5 Experimental An Optical "Black Box" Problem Solution APhO 2011 Experimental problem 5, An Optical "Black Box"
2010
Taiwan
Theory 3 problems
1 Theory Particles and Waves Problem Solution APhO 2010 Theory problem 1, Particles and Waves 2 Theory Strong Resistive Electromagnets Problem Solution APhO 2010 Theory problem 2, Strong Resistive Electromagnets 3 Theory Electron and Gas Bubbles in Liquids Problem Solution APhO 2010 Theory problem 3, Electron and Gas Bubbles in Liquids Experimental 2 problems
4 Experimental Magnetic Force Probe Problem Solution APhO 2010 Experimental problem 4, Magnetic Force Probe 5 Experimental Understanding Semiconductor Lasers Problem Solution APhO 2010 Experimental problem 5, Understanding Semiconductor Lasers
2009
Thailand
Theory 3 problems
1 Theory Rolling Cylinders Problem Solution APhO 2009 Theory problem 1, Rolling Cylinders 2 Theory A Self-excited Magnetic Dynamo Problem Solution APhO 2009 Theory problem 2, A Self-excited Magnetic Dynamo 3 Theory The Leidenfrost Phenomenon Problem Solution APhO 2009 Theory problem 3, The Leidenfrost Phenomenon Experimental 2 problems
4 Experimental The Earth's Horizontal Magnetic Field Problem Solution APhO 2009 Experimental problem 4, The Earth's Horizontal Magnetic Field 5 Experimental Oscillation of Water-Filled Vessel Problem Solution APhO 2009 Experimental problem 5, Oscillation of Water-Filled Vessel
2008
Mongolia
Theory 3 problems
1 Theory Tea Ceremony and Physics of Bubbles Problem Solution APhO 2008 Theory problem 1, Tea Ceremony and Physics of Bubbles 2 Theory Ionic Crystal, Yukawa-type Potential and Pauli Principle Problem Solution APhO 2008 Theory problem 2, Ionic Crystal, Yukawa-type Potential and Pauli Principle 3 Theory How does a superluminal object look like? Problem Solution APhO 2008 Theory problem 3, How does a superluminal object look like? Experimental 1 problem The Physics of Sound Wave Problem 4 Experimental The Physics of Sound Wave Problem APhO 2008 Experimental problem 4, The Physics of Sound Wave
2007
China
Theory 3 problems
1 Theory Back-and-Forth Rolling of a Liquid-Filled Sphere Problem Solution APhO 2007 Theory problem 1, Back-and-Forth Rolling of a Liquid-Filled Sphere 2 Theory Optical properties of an unusual material Problem Solution APhO 2007 Theory problem 2, Optical properties of an unusual material 3 Theory Specific heat of free electron gas at constant volume Problem Solution APhO 2007 Theory problem 3, Specific heat of free electron gas at constant volume Experimental 2 problems
4 Experimental Using the Interference Method to Measure the Thermal Expansion Coefficient and Temperature Coefficient of Refractive Index of Glass Problem Solution APhO 2007 Experimental problem 4, Using the Interference Method to Measure the Thermal Expansion Coefficient and Temperature Coefficient of Refractive Index of Glass 5 Experimental Measurement of Liquid Electric Conductivity Problem Solution APhO 2007 Experimental problem 5, Measurement of Liquid Electric Conductivity
2006
Kazakhstan
Theory 3 problems
1 Theory Laser cooling of atoms Problem Solution APhO 2006 Theory problem 1, Laser cooling of atoms 2 Theory Oscillator damped by sliding friction Problem Solution APhO 2006 Theory problem 2, Oscillator damped by sliding friction 3 Theory Three Problems Problem Solution APhO 2006 Theory problem 3, Three Problems Experimental 1 problem Specific heat of aluminum and latent heat of evaporation Problem Solution 4 Experimental Specific heat of aluminum and latent heat of evaporation Problem Solution APhO 2006 Experimental problem 4, Specific heat of aluminum and latent heat of evaporation
2005
Indonesia
Problems 3 problems
1 Spring Cylinder With Massive Piston Problem Solution APhO 2005 problem 1, Spring Cylinder With Massive Piston 2 Magnetic Focusing Problem Solution APhO 2005 problem 2, Magnetic Focusing 3 Light Deflection by a Moving Mirror Problem Solution APhO 2005 problem 3, Light Deflection by a Moving Mirror 4 Determination of Shapes by Reflection not published 5 Magnetic Braking on an Inclined Plane not published
2004
Vietnam
Theory 3 problems
1 Theory Measure the mass in the weightless state Problem Solution APhO 2004 Theory problem 1, Measure the mass in the weightless state 2 Theory Optical fiber Problem Solution APhO 2004 Theory problem 2, Optical fiber 3 Theory Compression and expansion of a two gases system Problem Solution APhO 2004 Theory problem 3, Compression and expansion of a two gases system Experimental 2 problems
4 Experimental Hall Effect and Magnetoresistivity Effect Problem Solution APhO 2004 Experimental problem 4, Hall Effect and Magnetoresistivity Effect 5 Experimental Black Box Problem Solution APhO 2004 Experimental problem 5, Black Box
2003
Thailand
Theory 3 problems
1 Theory Satellite's orbit transfer Problem Solution APhO 2003 Theory problem 1, Satellite's orbit transfer 2 Theory Optical Gyroscope Problem Solution APhO 2003 Theory problem 2, Optical Gyroscope 3 Theory Plasma Lens Problem Solution APhO 2003 Theory problem 3, Plasma Lens Experimental 2 problems
4 Experimental Determination of Capacitance Problem Solution APhO 2003 Experimental problem 4, Determination of Capacitance 5 Experimental Cylindrical Bore Problem Solution APhO 2003 Experimental problem 5, Cylindrical Bore
2002
Singapore
Theory 3 problems
1 Theory Vibrations of a Linear Crystal Lattice Problem Solution APhO 2002 Theory problem 1, Vibrations of a Linear Crystal Lattice 2 Theory The Rail Gun Problem Solution APhO 2002 Theory problem 2, The Rail Gun 3 Theory Water Fabrication Problem Solution APhO 2002 Theory problem 3, Water Fabrication Experimental 2 problems
4 Experimental Part A: Measurement of Reflectance and Determination of Refractive Index Problem APhO 2002 Experimental problem 4, Part A: Measurement of Reflectance and Determination of Refractive Index 5 Experimental Part B: Frequency of Vibration of a Tuning Fork Problem Solution APhO 2002 Experimental problem 5, Part B: Frequency of Vibration of a Tuning Fork
2001
Taiwan
Theory 3 problems
1 Theory When will the Moon become a Synchronous Satellite? Problem Solution APhO 2001 Theory problem 1, When will the Moon become a Synchronous Satellite? 2 Theory Motion of an Electric Dipole in a Magnetic Field Problem Solution APhO 2001 Theory problem 2, Motion of an Electric Dipole in a Magnetic Field 3 Theory Thermal Vibrations of Surface Atoms Problem Solution APhO 2001 Theory problem 3, Thermal Vibrations of Surface Atoms 4 Experimental Basic Characteristics of Solar Cells Problem Solution APhO 2001 Experimental problem 4, Basic Characteristics of Solar Cells
2000
Indonesia
Problems 3 problems
1 Eclipses of the Jupiter's Satellite Problem Solution APhO 2000 problem 1, Eclipses of the Jupiter's Satellite 2 Detection of Alpha Particles Problem Solution APhO 2000 problem 2, Detection of Alpha Particles 3 Stewart-Tolman Effect Problem Solution APhO 2000 problem 3, Stewart-Tolman Effect 4 Determination of the Density of Oil not published 5 Determination of the Stefan-Boltzmann Constant not published
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