Constants Topics: Values Energy Equivalents Searchable Bibliography Background Constants Bibliography Constants, Units & Uncertainty home page

Introduction to the constants for nonexperts Introduction 1900 - 1920 1920 - 1940 1940 - 1960 Current (index) Index of experiments described Elementary charge Oil drop experiments Using the Avogadro constant and the Faraday constant Fine-structure constant Quantum Hall effect and calculable cross capacitor Fine structure of atomic hydrogen Changes in the atomic energy states induced by irradiation with microwaves Free electron g factor Change in spin direction of trapped electrons with prealigned spins Ground state hyperfine splitting in atomic hydrogen Hydrogen maser Gyromagnetic ratio of the proton Precession frequency of protons in a magnetic field Magnetic moment of the proton Acceleration of protons in a magnetic field using radio-frequency fields Newtonian gravitational constant Deflection of a plumb line from the vertical Measuring the period of a pendulum's swing Ratio of the electron charge to the electron mass Deflection of beams of free electrons by electric and magnetic fields Ratio of Planck's constant to the elementary charge The photoelectric effect Short wavelength limit of the continuous x-ray spectrum Velocity of light in vacuum 16th-18th centuries: Handheld lanterns, astronomical measurement 19th-20th centuries: Reflecting light between a rotating mirror and a fixed mirror

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