Experiments you can run yourself.
The law of radioactive decay: why after each half-life one half of the nuclei remains. An interactive simulation, the formula, and C-14 dating.
The Bohr model of the atom: why an excited electron emits light and where the spectral lines of elements come from. An interactive simulation of energy levels.
Light ejects electrons from a metal only above the threshold frequency f₀=W/h. The kinetic energy E_k=hf−W depends on frequency, while intensity controls only the number of electrons.
The greater the particle's momentum, the shorter its matter wave.
The more precisely we know the position, the less precisely we know the momentum.
Electrons produce a diffraction pattern on a crystal — confirming de Broglie waves (Nobel Prize 1937).
The scattered photon has a longer wavelength — proof that light carries momentum (Nobel 1927).
The current dips at evenly spaced voltages — the atom's energy is quantised (Nobel Prize 1925).
A photon carries momentum — the right light can slow down and cool atoms (Nobel 1997).
Population inversion lets one photon trigger an avalanche of identical photons (Nobel Prize 1964).
The tunnelling current depends exponentially on the tip–surface distance — which makes it possible to image single atoms (Nobel Prize in Physics 1986).
When a magnetic field is switched on, an atom's spectral line splits into several closely spaced lines (Nobel Prize in Physics 1902).