IPhO Problems and Solutions

2026

Colombia

Three problems

Problem Solution

Cooking with sunlight?

Problem Solution

Chasing the absolute zero

Problem Solution

E: Ideal Gas, Vapor Pressure, and Heat Conduction

Problem Solution

2025

France

Hydrogen and galaxies

Problem Solution

Cox's Timepiece

Problem Solution

Champagne!

Problem Solution

E: Earth's magnetic field measurement

Problem Solution

E: Sand craters and dunes

Problem Solution

Strongly correlated Fermi gases (Theory Backup)

Problem Solution

2024

Iran

Greenhouse Effect

Problem Solution

Trapping Ions and Cooling Atoms

Problem Solution

Black Widow Pulsar

Problem Solution

E: Heat Conduction in a Copper Rod

Problem Solution

E: Diffraction from Phase Steps

Problem Solution

2023

Japan

Soil Colloids

Neutron Stars

Water and Objects

E: Mass Measurement

E: Birefringence

2022

Switzerland

Permanent magnets

Problem Solution

James Webb Space Telescope

Scaling laws

E: Planet

E: Cylindrical Diode

2021

Lithuania

Planetary Physics

Problem Solution

Electrostatic Lens

Problem Solution

Particles and Waves

Problem Solution

E: Non-ideal Capacitors

Problem Solution

E: LEDs

Problem Solution

2020

IdPhO

Problem Mix

Anisotropic Friction

Laser Technologies

E: Crystallography

2019

Israel

Zero-length springs and slinky coils

Problem Solution

The Physics of a Microwave Oven

Problem Solution

Thermoacoustic Engine

Problem Solution

E: Optical Measurements

Problem Solution

E: Wiedemann-Franz Law

Problem Solution

2018

Portugal

LIGO-GW150914

Problem Solution

Where is the neutrino?

Problem Solution

Physics of Live Systems

Problem Solution

E: Paper Transistor

Problem Solution

E: Viscoelasticity of a Polymer Thread

Problem Solution

2017

Indonesia

Dark Matter

Problem Solution

Earthquake, Volcano and Tsunami

Problem Solution

Cosmic Inflation

Problem Solution

E: Optics of a Salt Solution

Problem Solution

E: 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

E: Electrical Conductivity in 2D

Problem Solution

E: Jumping Beads

Problem Solution

2015

India

Particles from the Sun

Problem Solution

The Extremum Principle

Problem Solution

The Design of a Nuclear Reactor

Problem Solution

E: Diffraction due to Helical Structure

Problem Solution

E: Diffraction due to Surface Tension

Problem Solution

2014

Kazakhstan

Three Problems

Van der Waals Gas

Gas Discharge

E: To see invisible!

2013

Denmark

The Maribo Meteorite

Problem Solution

Plasmonic Steam Generator

Problem Solution

The Greenlandic Ice Sheet

Problem Solution

E: Speed of Light

Problem Solution

E: Solar Cells

Problem Solution

2012

Estonia

Focus on sketches

Problem Solution

Kelvin water dropper

Problem Solution

Protostar formation

Problem Solution

E: The Magnetic Permeability of Water

Problem Solution

E: 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

E: Blackbox: Capacitive Displacement Sensor

Problem Solution

E: 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

E: Elasticity of Sheets

Problem Solution

E: 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

E: Wavelength of a Diode Laser

Problem Solution

E: 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

E: Differential Thermometric Method

Problem Solution

2007

Iran

Black Holes

Problem Solution

Air Bags

Problem Solution

Binary Stars

Problem Solution

E: 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

E: 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

E: Planck's Constant in an Incandescent Lamp

Problem Solution

2004

Korea

“Ping-Pong” Resistor

Problem Solution

Rising Balloon

Problem Solution

Atomic Probe Microscope

Problem Solution

E: 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

E: 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

E: Physical Constants with Electrolysis

Problem Solution

E: Optical Black Box

Problem Solution

2001

Turkey

Four Problems

Problem Solution

Binary Star System

Problem Solution

Magnetohidrodynamic (mhd) Generator

Problem Solution

E: Rotating Liquid

Problem Solution

2000

United Kingdom

Five Problems

Problem Solution

Cathode Ray Tube

Problem Solution

Gravitational Waves and Light

Problem Solution

E: Cdrom Spectrometer

Problem

E: 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

E: 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

E: Electromagnetism

Problem

1997

Canada

Scalings

Problem Solution

Nuclear Masses and Stability

Problem Solution

Solar-Powered Aircraft

Problem Solution

E: Characterization of the Bimorph

Problem Solution

1996

Norway

Five Problems

Problem Solution

Dynamics of Electrons and Cylinders

Problem Solution

Moon and Tides

Problem Solution

E: Gravity and Magnetism

Problem Solution

1995

Australia

Gravitational Red Shift and Stellar Mass

Problem Solution

Sound Propagation

Problem Solution

Cylindrical Buoy

Problem Solution

E: Terminal Velocity in a Viscous Liquid

Problem Solution

E: Difiraction 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

E: Light Reflectivity of a Transparent Dielectric

Problem Solution

E: Two Terminal Black Box

Problem Solution

1993

USA

Atmospheric Electricity

Problem Solution

Laser Forces on a Transparent Prism

Problem Solution

Electron Beam

Problem Solution

E: Heat of Vaporization of Nitrogen

Problem Solution

E: Magnetic Moments and Fields

Problem Solution

1992

Finland

A Rotating Satellite

Problem Solution

The Longitudinal Motion of a Linear Molecule

Problem Solution

A Satellite in Sunshine

Problem Solution

E: Electric Breakdown of Air

Problem Solution

E: A Grating and Optical Filters

Problem Solution

1991

Cuba

Friction on Impact

Problem Solution

Relativistic Square

Problem Solution

Cooling Atoms by Laser

Problem Solution

E: Three Terminal Black Box

Problem Solution

1990

Netherlands

X-ray Diffraction from a Crystal

Problem Solution

Electric Experiments in the Magnetosphere

Problem Solution

The Rotating Neutron Star

Problem Solution

E: LED Efficiency

Problem Solution

E: Two Magnets

Problem Solution

1989

Poland

Boiling Liquids

Problem Solution

Rotating Masses

Problem Solution

Proton Microscope

Problem Solution

E: 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

E: Polarized Light

Problem Solution

E: Electron Tube

Problem Solution

1987

East Germany

Ascending Moist Air

Problem Solution

Electrons in a Magnetic Field

Problem Solution

Infinite LC-grid

Problem Solution

E: Refractive Indices

Problem Solution

1986

United Kingdom

Wave Interference

Seismic Waves

Masses and Springs

E: Pendant Drop

E: Microcomputer

1985

Yugoslavia

Antenna Array

Problem Solution

Hall Effect

Problem Solution

Escaping the Solar System

Problem Solution

E: Brass Disk

Problem Solution

E: Permanent Magnets

Problem Solution

1984

Sweden

Mirage

Problem Solution

Seiching

Problem Solution

Electrical Filter

Problem Solution

E: Diode, Capacitor and Resistor

Problem Solution

E: Glow Discharge Lamp

Problem Solution

1983

Romania

Jumping Particle

Problem Solution

Different kind of Oscillation

Prisms

Compton Scattering

IPhO's logo

1982

West Germany

Fluorescent lamp

Problem Solution

Oscillating coat hanger

Problem Solution

Hot-air-balloon

Problem Solution

E: Lens Experiment

Problem Solution

E: Motion of a Rolling Cylinder

Problem Solution

1981

Bulgaria

Gas Container Rocket

Problem Solution

Electric Lamp

Problem Solution

Detecting Astronomical Radiowaves

Problem Solution

E: Elastic Rubber Cord

Problem Solution

1979

Soviet Union

To the Moon!

Problem Solution

Influence of Humidity on Scales

Problem Solution

Reflectors on the Moon

Problem Solution

E: 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

E: 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

E: Semiconductor Element

Problem Solution

1974

Poland

Hydrogen Atoms Colliding

Problem Solution

Bending Light

Problem Solution

Surviving with Thermodynamics

Problem Solution

E: 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

E: 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

E: 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

E: 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

Mixing Toluene

Glass Semi-cylinder

E: Three Black Boxes

1967

Poland

Shooting a Ball

Problem Solution

Infinite Network of Resistors

Heating Balls

Heating a Vessel

E: Heating Petroleum