InPhO Problems and Solutions

The second of five stages in the Indian selection, running since 1998. Some 300 to 400 students reach it out of the more than 40,000 who sit the NSEP screening exam below it.

2025

India

Problems5 problemsProblemsSolutions
  • 1Flywheel moment of inertia*not published
  • 2Motor-generator gearbox efficiency*not published
  • 3Heart-shaped thermodynamic cycle*not published
  • 4Magnetic Black Box*not published
  • 5Metalens phase profile and lens equation*not published

2024

India

Problems6 problemsProblemsSolutions
  • 1Coulomb force versus distance*not published
  • 2Prism image formation problems*not published
  • 3Chandrayaan-3 orbital maneuvers*not published
  • 4Conducting loop entering magnetic field*not published
  • 5Thermal Tussle of Pistons*not published
  • 6Water-filled tube resonance*not published

2023

India

Problems5 problemsProblemsSolutions
  • 1Bouncing ball classroom height*not published
  • 2Photoelectric timing and current*not published
  • 3Maximum work in linear process*not published
  • 4Charged ring near charged rod*not published
  • 5Smartphone screen air gap*not published

2022

India

Problems5 problemsProblemsSolutions
  • 1Damped spring-block on rough table*not published
  • 2Trinity fireball energy estimate*not published
  • 3Deflating spherical balloon*not published
  • 4Pendulum length error and slope*not published
  • 5Unknown network with ammeter and voltmeter*not published

2021

India

Problems5 problemsProblemsSolutions
  • 1Ammeter-voltmeter resistance measurement*not published
  • 2Van der Waals adiabatic work*not published
  • 3Classical atom collapse time*not published
  • 4Parallel beam through three lenses*not published
  • 5Ball throw on rotating merry-go-round*not published

2020

India

Problems5 problemsProblemsSolutions
  • 1Gas with unusual equation of state*not published
  • 2Spinning charged cylinder in decaying field*not published
  • 3Bohr model ionization energies*not published
  • 4Doppler shift from circular motion*not published
  • 5Bullet impact on tethered rod*not published

2019

India

Problems7 problemsProblemsSolutions
  • 1Sound path in stratified atmosphere*not published
  • 2Electrons in a 1D box*not published
  • 3Falling chain from support*not published
  • 4Compressible liquid in a tube*not published
  • 5Rod on rails with capacitor*not published
  • 6Van der Waals Diesel cycle*not published
  • 7Magnet sliding on inclined plane*not published

2018

India

Problems7 problemsProblemsSolutions
  • 1Nuclear force constants A, B, C*not published
  • 2Shadow of sphere with liquid*not published
  • 3Infinite resistor ladder*not published
  • 4Hourglass scale reading*not published
  • 5Floating magnet and Bohr magneton*not published
  • 6Van der Waals gas properties*not published
  • 7Water level in inverted cylinder*not published

2017

India

Problems6 problemsProblemsSolutions
  • 1Gravitational wave orbital decay*not published
  • 2Mercury mirror image formation*not published
  • 3Colliding blocks on incline*not published
  • 4Otto cycle analysis*not published
  • 5Sliding rod in magnetic field*not published
  • 6Prism dispersion and refractive index*not published

2016

India

Problems6 problemsProblemsSolutions
  • 1U-shaped glass rod tir*not published
  • 2Field near hole in charged shell*not published
  • 3Two-stage rocket optimization*not published
  • 4Blackbody radiation gas expansion*not published
  • 5Black box delta resistances*not published
  • 6Yukawa potential and deuteron binding*not published

2015

India

Problems6 problemsProblemsSolutions
  • 1Particle on logarithmic spiral track*not published
  • 2Cylinder on accelerating incline*not published
  • 3Induced field and potential on sphere*not published
  • 4Point charge near grounded sphere*not published
  • 5Point charge near charged sphere*not published
  • 6Refraction and Interference in Slab*not published

2014

India

Problems8 problemsProblemsSolutions
  • 1Sliding rod on parabolic wire*not published
  • 2Two blocks with spring under force*not published
  • 3Superposed vibrations and ray path*not published
  • 4Refrigerator in a hut*not published
  • 5Men jumping off a cart*not published
  • 6Equilibrium of test charge*not published
  • 7Bohr-Wheeler fission limit*not published
  • 8Magnetic field to hold current frame*not published

2013

India

Problems7 problemsProblemsSolutions
  • 1Capacitor with graded dielectric*not published
  • 2Electron diffraction from crystal surface*not published
  • 3Accelerating bicycle with torque*not published
  • 4Spherical mirror aberration*not published
  • 5Torque on loop between wires*not published
  • 6Central force orbit stability*not published
  • 7Brunt-Väisälä balloon oscillations*not published

2012

India

Problems5 problemsProblemsSolutions
  • 1Rotating rod struck by falling balls*not published
  • 2Convex mirror approach speed*not published
  • 3Cloud formation height estimate*not published
  • 4Solenoid fields and inductance*not published
  • 5Rydberg atom ionization fields*not published

2011

India

Problems7 problemsProblems
  • 1Electron near current-carrying wire*not published
  • 2Young's double slit with time-varying liquid*not published
  • 3Carnot cycle state variables*not published
  • 4Modified Coulomb Bohr model*not published
  • 5Electron motion in crossed fields*not published
  • 6Collision of block with spring-coupled pair*not published
  • 7Cubic potential motion analysis*not published

2010

India

Problems5 problemsProblemsSolutions
  • 1Two skaters exchanging a ball*not published
  • 2Adiabatic cylinder with three gas parts*not published
  • 3Achromatic prism pair deviation*not published
  • 4Charged rotating cylindrical shell*not published
  • 5Technetium decay and blood volume*not published

2008

India

Problems7 problemsProblems
  • 1Bohr orbit from constants*not published
  • 2Projectile with linear air resistance*not published
  • 3Free Standing Equatorial Tower*not published
  • 4Heat transfer between two walls*not published
  • 5Chromatic aberration in plano-convex lens*not published
  • 6Speed of light via AC forces*not published
  • 7Ring in oscillating magnetic field*not published