IPhO Problems and Solutions

2025

France

Hydrogen and galaxies

📝Problem  💡Solution

Cox’s Timepiece

📝Problem  💡Solution

Champagne!

📝Problem  💡Solution

Exp: Earth’s magnetic field measurement

📝Problem 

Exp: Sand craters and dunes

📝Problem

Backup: Strongly correlated Fermi gases

📝Problem

2024

Iran

Greenhouse Effect

📝Problem  💡Solution

Trapping Ions and Cooling Atoms

📝Problem  💡Solution

Black Widow Pulsar

📝Problem  💡Solution

Exp: Heat Conduction in a Copper Rod

📝Problem 💡Solution

Exp: Diffraction from Phase Steps

📝Problem 💡Solution

2023

Japan

Soil Colloids

📝Problem  💡Solution

Neutron Stars

📝Problem  💡Solution

Water and Objects

📝Problem  💡Solution

Exp: Mass Measurement

📝Problem 💡Solution

Exp: Birefringence

📝Problem 💡Solution

2022

Switzerland

Permanent Magnets

📝Problem  💡Solution

James Webb Space Telescope

📝Problem  💡Solution

Scaling Laws

📝Problem  💡Solution

Exp: Planet

📝Problem 💡Solution

Exp: Cylindrical Diode

📝Problem 💡Solution

2021

Lithuania

Planetary Physics

📝Problem  💡Solution

Electrostatic Lens

📝Problem  💡Solution

Particles and Waves

📝Problem  💡Solution

Exp: Non-ideal Capacitors

📝Problem 💡Solution

Exp: LEDs

📝Problem 💡Solution

2020

Online

Problem Mix

📝Problem  💡Solution

Anisotropic Friction

📝Problem  💡Solution

Laser Technologies

📝Problem  💡Solution

Exp: Crystallography

📝Problem 💡Solution

2019

Israel

Zero-length Springs and Slinky Coils

📝Problem  💡Solution

The Physics of a Microwave Oven

📝Problem  💡Solution

Thermoacoustic Engine

📝Problem  💡Solution

Exp: Optical Measurements

📝Problem 💡Solution

Exp: Wiedemann-Franz Law

📝Problem 💡Solution

2018

Portugal

LIGO-GW150914

📝Problem 💡Solution

Where is the neutrino?

📝Problem  💡Solution

Physics of Live Systems

📝Problem  💡Solution

Exp: Paper Transistor

📝Problem 💡Solution

Exp: Viscoelasticity of a Polymer Thread

📝Problem 💡Solution

2017

Indonesia

Dark Matter

📝Problem  💡Solution

Earthquake, Volcano and Tsunami

📝Problem  💡Solution

Cosmin Inflation

📝Problem  💡Solution

Exp: Optics of a Salt Solution

📝Problem 💡Solution

Exp: Earthquake and Volcano Sensing

📝Problem 💡Solution

2016

Switzerland

Two Problems in Mechanics

📝Problem  💡Solution

Nonlinear Dynamics in Electric Circuits

📝Problem  💡Solution

Large Hadron Collider

📝Problem  💡Solution

Exp: Electrical Conductivity in 2D

📝Problem 💡Solution

Large Hadron Collider

📝Problem  💡Solution

2015

India

Particles from the Sun

📝Problem  💡Solution

The Extremum Principle

📝Problem  💡Solution

The Design of a Nuclear Reactor

📝Problem  💡Solution

Exp: Diffraction due to Helical Structure

📝Problem 💡Solution

Exp: Diffraction due to Surface Tension

📝Problem 💡Solution

2014

Kazakhstan

Three Problems

📝Problem  💡Solution

Van der Waals Gas

📝Problem  💡Solution

Gas Discharge

📝Problem  💡Solution

Exp: To see invisible!

📝Problem 💡Solution

2013

Denmark

The Maribo Meteorite

📝Problem  💡Solution

Plasmonic Steam Generator

📝Problem  💡Solution

The Greenlandic Ice Sheet

📝Problem  💡Solution

Exp: Speed of Light

📝Problem 💡Solution

Exp: Solar Cells

📝Problem 💡Solution

2012

Estonia

Focus on Sketches

📝Problem  💡Solution

Kelvin Water Dropper

📝Problem  💡Solution

Protostar Formation

📝Problem  💡Solution

Exp: The Magnetic Permeability of Water

📝Problem 💡Solution

Exp: Nonlinear Black Box

📝Problem 💡Solution

2011

Thailand

A Three-Body Problem and LISA

📝Problem  💡Solution

An Electrified Soap Bubble

📝Problem  💡Solution

Scattering of an Ion by a Neutral Atom

📝Problem  💡Solution

Exp: Blackbox: Capacitive Displacement Sensor

📝Problem 💡Solution

Exp: Mechanical Blackbox: A cylinder with a ball inside

📝Problem 💡Solution

2010

Croatia

Image of a Charge in a Metallic Object

📝Problem  💡Solution

Chimney Physics

📝Problem  💡Solution

Simple Model of an Atomic Nucleus

📝Problem  💡Solution

Exp: Elasticity of Sheets

📝Problem 💡Solution

Exp: Forces Between Magnets

📝Problem 💡Solution

2009

Mexico

Evolution of the Earth-Moon System

📝Problem  💡Solution

Doppler Laser Cooling and Optical Molasses

📝Problem  💡Solution

Why are Stars so Large?

📝Problem  💡Solution

Exp: Wavelength of a Diode Laser

📝Problem 💡Solution

Exp: Birefringence of Mica

📝Problem 💡Solution

2008

Vietnam

Water-Powered Rice-Pounding Mortar

📝Problem  💡Solution

Cherenkov Light and Ring Imaging Counter

📝Problem  💡Solution

Change of Air Temperature in the Atmosphere

📝Problem  💡Solution

Exp: Differential Thermometric Method

📝Problem 💡Solution

2007

Iran

Black Holes

📝Problem  💡Solution

Air Bags

📝Problem  💡Solution

Binary Stars

📝Problem  💡Solution

Exp: Band Gap of Semiconductor Thin Films

📝Problem 💡Solution

2006

Singapore

Gravity in a Neutron Interferometer

📝Problem  💡Solution

Watching a Rod in Motion

📝Problem  💡Solution

Five Estimations

📝Problem  💡Solution

Exp: Interference, Reflection and Diffraction

📝Problem 💡Solution

2005

Spain

An Ill Fated Satellite

📝Problem  💡Solution

Absolute Measurements of Electrical Quantities

📝Problem  💡Solution

Neutrons in a Gravitational Field

📝Problem  💡Solution

Exp: Plack’s Constant in an Incandescent Lamp

📝Problem 💡Solution

2004

Korea

“Ping-Pong” Resistor

📝Problem  💡Solution

Rising Balloon

📝Problem  💡Solution

Atomic Probe Microscope

📝Problem  💡Solution

Exp: Mechanical “Black Box”

📝Problem 💡Solution

2003

Taiwan

A Swing with a Falling Weight

📝Problem  💡Solution

A Piezoelectric Crystal Resonator

📝Problem  💡Solution

Neutrino Mass and Neutron Decay

📝Problem  💡Solution

Exp: Optical Properties of Laser Diode

📝Problem 💡Solution

2002

Indonesia

Ground-Penetrating Radar

📝Problem  💡Solution

Sensing Electrical Signals

📝Problem  💡Solution

A Heavy Vehicle Moving on an Inclined Road

📝Problem  💡Solution

Exp: Physical Constants with Electrolysis

📝Problem 💡Solution

Exp: Optical Black Box

📝Problem 💡Solution

2001

Turkey

Four Problems

📝Problem  💡Solution

Binary Star System

📝Problem  💡Solution

Magnetohydrodynamic (MHD) Generator

📝Problem  💡Solution

Exp: Rotating Liquid

📝Problem 💡Solution

2000

United Kingdom

Five Problems

📝Problem  💡Solution

Cathode Ray Tube

📝Problem  💡Solution

Gravitational Waves and Light

📝Problem  💡Solution

Exp: CDROM Spectrometer

📝Problem 

Exp: The Magnetic Puck

📝Problem 

1999

Italy

Absorption of Radiation by a Gas

📝Problem  💡Solution

Magnetic Field with a V-Shaped Wire

📝Problem  💡Solution

A Space Probe to Jupiter

📝Problem  💡Solution

Exp: Torsion Pendulum

📝Problem 💡Solution

1998

Iceland

Rolling of a Hexagonal Prism

📝Problem  💡Solution

Water under an Ice Cap

📝Problem  💡Solution

Faster than Light?

📝Problem  💡Solution

Exp: Electromagnetism

📝Problem 

1997

Canada

Scalings

📝Problem  💡Solution

Nuclear Masses and Stability

📝Problem  💡Solution

Solar-Powered Aircraft

📝Problem  💡Solution

Exp: Characterization of the Bimorph

📝Problem 💡Solution

1996

Norway

Five Problems

📝Problem  💡Solution

Dynamics of Electrons and Cylinders

📝Problem  💡Solution

Moon and Tides

📝Problem  💡Solution

Exp: Gravity and Magnetism

📝Problem 💡Solution

1995

Australia

Gravitational Red Shift and Stellar Mass

📝Problem  💡Solution

Sound Propagation

📝Problem  💡Solution

Cylindrical Buoy

📝Problem  💡Solution

Exp: Terminal Velocity in a Viscous Liquid

📝Problem 💡Solution

Exp: Diffraction and Scattering of Laser Light

📝Problem 💡Solution

1994

China

Relativistic Particle

📝Problem  💡Solution

Superconducting Magnet

📝Problem  💡Solution

Collision of Discs with Surface Friction

📝Problem  💡Solution

Exp: Light Reflectivity of a Transparent Dielectric

📝Problem 💡Solution

Exp: Two Terminal Black Box

📝Problem 💡Solution

1993

USA

Atmospheric Electricity

📝Problem  💡Solution

Laser Forces on a Transparent Prism

📝Problem  💡Solution

Electron Beam

📝Problem  💡Solution

Exp: Heat of Vaporization of Nitrogen

📝Problem  💡Solution

Exp: Magnetic Moments and Fields

📝Problem 💡Solution

1992

Finland

 Rotating Satellite

📝Problem  💡Solution

The Longitudinal Motion of a Linear Molecule

📝Problem  💡Solution

A Satellite in Sunshine

📝Problem  💡Solution

Exp: Electric Breakdown of Air

📝Problem 💡Solution

Exp: A Grating and Optical Filters

📝Problem 💡Solution

1991

Cuba

Friction of Impact

📝Problem  💡Solution

Relativistic Square

📝Problem  💡Solution

Cooling Atoms by Laser

📝Problem  💡Solution

Exp: Three Terminal Black Box

📝Problem 💡Solution

1990

Netherlands

X-Ray Diffraction from a Crystal

📝Problem  💡Solution

Electric Experiments  in the Magnetosphere

📝Problem  💡Solution

A Rotating Neutron Star

📝Problem  💡Solution

Exp: LED Efficiency

📝Problem 💡Solution

Exp: Two Magnets

📝Problem 💡Solution

1989

Poland

Boiling Liquids

📝Problem  💡Solution

Rotating Masses

📝Problem  💡Solution

Proton Microscope

📝Problem  💡Solution

Exp: Piezoelectric Discs

📝Problem 💡Solution

1988

Austria

Spectroscopy of Particle Velocities

📝Problem  💡Solution

Maxwell’s Wheel

📝Problem  💡Solution

Recombination of Ions in Ionized Gas

📝Problem  💡Solution

Exp: Polarized Light

📝Problem 💡Solution

Exp: Electron Tube

📝Problem 💡Solution

1987

East Germany

Ascending Moist Air

📝Problem  💡Solution

Electrons in a Magnetic Field

📝Problem  💡Solution

Infinite LC-grid

📝Problem  💡Solution

Exp: Refractive Indices

📝Problem 💡Solution

1986

United Kingdom

Wave Interference

📝Problem  💡Solution

Seismic Waves

📝Problem  💡Solution

Masses and Springs

📝Problem  💡Solution

Exp: Pendant Drop

📝Problem 💡Solution

Exp: Microcomputer

📝Problem 💡Solution

1985

Yugoslavia

Antenna Array

📝Problem  💡Solution

Hall Effect

📝Problem  💡Solution

Escaping the Solar System

📝Problem  💡Solution

Exp: Brass Disk

📝Problem 💡Solution

Exp: Permanent Magnets

📝Problem 💡Solution

1984

Sweden

Mirage

📝Problem  💡Solution

Seiching

📝Problem  💡Solution

Electrical Filter

📝Problem  💡Solution

Exp: Diode, Capacitor and Resistor

📝Problem 💡Solution

Exp: Glow Discharge Lamp

📝Problem 💡Solution

1983

Romania

Jumping Particle

📝Problem  💡Solution

Different kind of Oscillation

📝Problem  💡Solution

Prisms

📝Problem  💡Solution

Compton Scattering

📝Problem 💡Solution

IPhO’s LOGO

📝Problem 💡Solution

1982

West Germany

Fluorescent Lamp

📝Problem  💡Solution

Oscillating Coat Hanger

📝Problem  💡Solution

Hot-air-balloon

📝Problem  💡Solution

Exp: Lens Experiment

📝Problem 💡Solution

Exp: Motion of a Rolling Cylinder

📝Problem 💡Solution

1981

Bulgaria

Gas Container Rocket

📝Problem  💡Solution

Electric Lamp

📝Problem  💡Solution

Detecting Astronomical Radiowaves

📝Problem  💡Solution

Exp: Elastic Rubber Cord

📝Problem 💡Solution

1979

Soviet Union

To the Moon!

📝Problem  💡Solution

Influence of Humidity on Scales

📝Problem  💡Solution

Influence of Humidity on Scales

📝Problem  💡Solution

Exp: Black Box

📝Problem 💡Solution

1977

Czechoslovakia

Otto Cycle

📝Problem  💡Solution

Rectangular Soap Film

📝Problem  💡Solution

Electron Gun

📝Problem  💡Solution

1976

Hungary

Spinning Block inside a Sphere

📝Problem  💡Solution

A Valve in a Cylinder

📝Problem  💡Solution

Air Bubble inside a Glass Sphere

📝Problem  💡Solution

Exp: Thermal Properties of the X Material

📝Problem 💡Solution

1975

East Germany

Rotating Rod

📝Problem  💡Solution

Thick Lens

📝Problem  💡Solution

Ions in a Magnetic Field

📝Problem  💡Solution

Exp: Semiconductor Element

📝Problem 💡Solution

1974

Poland

Hydrogen Atoms Colliding

📝Problem  💡Solution

Bending Light

📝Problem  💡Solution

Surviving with Thermodynamics

📝Problem  💡Solution

Exp: Diodes in a Black Box

📝Problem 💡Solution

1972

Romania

Three Cylinders

📝Problem  💡Solution

Molecular Physics

📝Problem  💡Solution

Dielectric Liquid

📝Problem  💡Solution

Geometrical Optics and Interference

📝Problem 💡Solution

Exp: Two Cylinders

📝Problem 💡Solution

1971

Bulgaria

Connected Masses on a Prism

📝Problem  💡Solution

Mercury Barometer

📝Problem  💡Solution

Batteries, Capacitors and Resistors in a Cube

📝Problem  💡Solution

Spherical Aquarium

📝Problem 💡Solution

Exp: Rheostat Dissipation

📝Problem 💡Solution

1970

Soviet Union

Carrying a Bar

📝Problem  💡Solution

A Chemistry Problem (Salt Crystals)

📝Problem  💡Solution

Spherical Capacitors

📝Problem  💡Solution

A Telescope with a Spherical Mirror

📝Problem 💡Solution

Exp: Three Lenses

📝Problem 💡Solution

1969

Czechoslovakia

Three Carts

📝Problem  💡Solution

Water inside a Copper Calorimeter

📝Problem  💡Solution

Suspended Charged Ball

📝Problem  💡Solution

Glass Plate above a Glass Cube

📝Problem 💡Solution

1968

Hungary

Block and Cylinder on an Inclined Plane

📝Problem  💡Solution

Mixing  Toluene

📝Problem  💡Solution

Glass Semi-cylinder

📝Problem  💡Solution

Exp: Three Black Boxes

📝Problem 💡Solution

1967

Poland

Shooting a Ball

📝Problem  💡Solution

Infinite Network of Resistors

📝Problem  💡Solution

Heating Balls

📝Problem  💡Solution

Heating a Vessel

📝Problem 💡Solution

Exp: Heating Petroleum

📝Problem 💡Solution‎

‎