Modern Physics Laboratory - Modern Physics Laboratory

Fourteen experiments, one per week, one per chapter of Modern Physics: Relativity, Quantum Theory, and the Structure of Matter. Most bench work is planned for a three-hour laboratory period. Slow counting measurements, especially the Week 14 muon telescope, need runs outside that period; arrange these with the instructor. The experiments use apparatus that a small department can maintain and are analyzed in Python.

The schedule¶

Table 1:Weekly experiments and the chapter each accompanies

Week	Experiment	Chapter	Central measurement
1	Michelson Interferometer and the Ether Null Result	1	Laser wavelength at percent-level precision; sensitivity to a modeled ether drift
2	The Speed of Light	2	Light’s speed in air by time of flight over a few meters
3	Relativistic Electrons from Beta Decay	3	Conditional $\beta$ endpoint estimate from the terminal absorption range; relativistic $v/c$
4	Interference of Light	4	Slit separation; hair thickness from air-wedge fringes when resolved
5	Diffraction and the Resolution Limit	5	Slit width, grating pitch, and the Rayleigh criterion
6	Planck’s Constant from Light-Emitting Diodes	6	Conditional LED estimate of $h$ ; tungsten lamp’s effective power–temperature exponent
7	The Quantum Eraser	7	Fringe visibility versus which-path information
8	Tunneling by Frustrated Total Internal Reflection	8	Thick-gap transmission decay; comparison with a quantum barrier
9	Eigenmodes, Degeneracy, and Nodal Patterns	9	Cavity resonances, symmetry splitting, and plate nodal patterns
10	The Balmer Series and the Rydberg Constant	10	Balmer line wavelengths and an uncertainty-bounded estimate of $R_{\mathrm H}$
11	Alkali Spectra and the Quantum Defect	11	Sodium D splitting; state-specific defects where weak lines are detected
12	Molecular Fluorescence and the Stokes Shift	12	Absorption and emission spectra; Beer–Lambert law
13	Counting Statistics and Half-Life	13	Poisson counting test, a half-life, and an effective gamma attenuation coefficient
14	A Cosmic-Ray Muon Telescope	14	Penetrating-particle coincidences; angular trend with long runs; conditional muon survival model

What every experiment file contains¶

Each experiment is a single self-contained Markdown file with the same sections in the same order, so that a student who has done one lab knows where to look in all the others:

Objectives — what you should be able to do afterwards.
Textbook connection — the sections of the chapter this lab tests.
Theory — the derivation you need, and nothing more.
Pre-lab — questions to be answered in your notebook before you arrive. These are collected at the start of the period.
Apparatus — a checklist of what is on the bench.
Safety — read it; the laser and source labs are not optional reading.
Procedure — numbered steps, with instructor checkpoints marked [ ].
Analysis — what to fit, how, and with what uncertainty model. Python scaffolding is provided; the physics is not.
Post-lab questions — what goes in the discussion section of your report.
Going further — optional extensions for students who finish early.

Python instead of point-and-click. Analysis is done in Jupyter with numpy, scipy.optimize, and matplotlib. Fits report uncertainties using the model appropriate to the data, including Poisson likelihood intervals for sparse counts. Quantitative results state a value, an uncertainty or bound, and a unit. Old .cap and .cmbl data files remain readable by exporting to CSV; see The Python Toolkit.

Uncertainty is the through-line. Nearly every experiment produces a number that has a known accepted value. The interesting question in each case is not whether the number is close, but whether the discrepancy is consistent with the quoted uncertainty. That question is worth more of the grade than the measurement itself, and the rubric says so.