Experimental Physics Guide

Before you touch any apparatus

Olympiads mark clear reasoning just as heavily as a 'correct' final number. Get into these habits from day one.

• Read the entire question before setting up. Underline what is to be measured, what is to be plotted, and what quantities must be computed.
• Plan your procedure: identify independent/dependent/control variables and do a 2-minute dry run in your head.
• Estimate orders of magnitude. If your answer is 1000× off, stop and check units.
• Never guess the apparatus: draw a rough circuit or ray diagram first, then assemble.

Error analysis & uncertainty

Learn a minimal, reliable set of rules you can actually use under time pressure.

• Identify type A (repeated) vs type B (instrument) uncertainties. [TO VERIFY official treatment]
• For a single reading: take half the smallest division or the stated precision.
• For repeated readings, use standard deviation of the mean when n≥5, else a reasonable range.
• Propagation: use linear approximation (sum in quadrature where appropriate) — know when to be conservative.
• Give uncertainties in one or two sig figs and the final value to the same decimal place.
• Always include a reasonable absolute/relative uncertainty on your final answer.

Graphs, fitting & calculations

Most olympiads want to see you extract a physical quantity from a straight line.

• Plot the graph as instructed — label axes with quantity, unit and scale. Choose scales to use >50% of the paper.
• Mark points clearly (×, not • alone). Draw the best-fit line with a ruler, not by 'connecting dots'.
• Use large triangles (spanning at least half the line) to find slope; avoid using two plotted points unless told to.
• Compute intercepts if asked and state them with uncertainty if possible.
• When linearising (e.g. T^2 vs L), write the theoretical relation and say what slope represents.

Common experiments to practise

These appear often at national camp and international level. Practise with whatever you have.

• Pendulum: T vs L, g from slope; discuss damping and large-angle effect.
• Young's modulus / bending of beam: careful measurements of small lengths.
• Ohm's law, metre bridge, potentiometer: zero errors and contact resistance.
• Focal length (lens/mirror), refractive index, interference basics.
• Moment of inertia / rotational dynamics — rare at pre-selection but common later.

Lab report checklist (time-limited)

If the exam gives a tight time, tick these off in order.

• Aim, apparatus, diagram (clear, labelled).
• Theory (key formulae only).
• Observations table: headings, units, at least enough data.
• Calculations: one sample calculation shown.
• Graph (if required), slope, final result with uncertainty.
• Sources of error, precautions and (if asked) possible improvements.
• Final answer boxed, units included.

Tips for Nepal-specific constraints

Be smart with limited resources — that can actually train you well.

• No oscilloscope at home? Use a timer on your phone for pendulums. PhET can simulate waveforms.
• Graphs by hand first — speed comes with practice, not fancy software.
• Form a small lab group at school: pool apparatus and critique each other's uncertainty calculations.
• Ask teachers to run one timed mock lab per term. [TO VERIFY — any lab mocks organised]

Useful resources

• Classic experimental physics setups: error analysis guide

  A practical primer on uncertainty, significant figures, graph linearisation and how to write a lab report that earns marks.

  NotesIntermediateSelection roundsNational campInternationalExperimental

  [TO VERIFY — source]

• Measurement tools simulation — PhET Interactive Simulations

  Free simulations for circuits, waves, forces and more. Useful to build intuition when you have no lab equipment at home.

  ToolBeginnerPre-selectionMechanicsElectromagnetismOpticsThermodynamics

  University of Colorado Boulderphet.colorado.edu ↗