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10 videos · 4 h 2 min
Explainer · YouTube
Khan Academy
A clear, chaptered tour of almost everything this session covers: discrete energy levels, the Bohr model and its energy-level diagram, excitation and de-excitation, hydrogen's spectrum, and how absorption lines identify the elements in distant stars. Its short look at orbital shapes previews chapter 16. Watch the energy-level diagram from about 5:37 and keep it in mind for the lab.
Explainer · YouTube
Physics Explained
A patient blackboard walk from Thomson's plum pudding and Rutherford's alpha scattering, through the instability of the nuclear atom, to Bohr's postulates, the quantization of angular momentum, the size of the atom, the energy levels and the visible hydrogen spectrum. Watch it after Part 5 and follow the algebra that turns L = nħ into Eₙ = −13.6 eV/n².
Explainer · YouTube
PBS Space Time
Matt O'Dowd tells how Cecilia Payne decoded stellar spectra in the 1920s and found that stars are made mostly of hydrogen and helium, against the expectations of the leading astronomers of her day. The perfect companion to Part 2.
Explainer · YouTube
Physics Explained
The calculation behind this section's death sentence for the planetary atom, done with classical physics alone: the electron's acceleration, the energy it radiates (the Larmor formula at 3:06), then a worked example. Check its result against the 1.6×10⁻¹¹ s quoted in the lesson.
Explainer · YouTube
Sixty Symbols
The astronomer Meghan Gray on hydrogen-alpha, the 656.28 nm line that 'would be high on the list' if astronomers had a favourite wavelength. It is this section's n = 3 to n = 2 leap, the 1.89 eV step that paints the Orion Nebula red, put to work by an astronomer, from the Sun's surface (1:41) to mapping star formation across galaxies (5:38).
Explainer · YouTube
Parth G
This section's closing callout as a video: the electron has no definite position, yet its most likely distance from the proton is the Bohr radius (3:36), which Parth then builds from ε₀, ħ and the electron's mass and works out (7:20). His chapter 'The Proton Has Infinite Mass?!' (7:59) is the fixed-nucleus approximation that Bohr dropped when Fowler pressed him.
Lecture · Royal Institution
The Royal Institution · Sean Carroll · 2020
Sean Carroll tells the story from Planck and Einstein through Bohr, de Broglie and Schrödinger, then argues that the measurement problem is still open and makes his case for the many-worlds interpretation. Notice where the history ends and his interpretation begins.
Demo · Harvard
Harvard Natural Sciences Lecture Demonstrations
Kirchhoff and Bunsen's sodium-flame experiment in 85 seconds: sodium bicarbonate burning in a Bunsen flame puts a black line into the yellow of a continuous spectrum. Harvard's demo team note that it is a stand-in for the sodium part of the Sun's Fraunhofer spectrum and does not split the 589.0/589.6 nm pair, so expect one dark line, not two.
Lecture · Center for Astrophysics
Center for Astrophysics · Donovan Moore
Donovan Moore, author of the biography 'What Stars Are Made Of', in a talk for the Center for Astrophysics, home of the Harvard College Observatory where Payne did the work. The jump lands on 'Starting the doctoral thesis', followed by 'A fundamental discovery' (22:13); rewind for her Cambridge years and the move to Harvard, far beyond the PBS Space Time briefing.
Lecture · American Physical Society
American Physical Society · John Heilbron
The historian John Heilbron (UC Berkeley and Oxford) on how Bohr built his atom, in the APS plenary 'The Quantum 100 Years Ago, the Quantum Today, and the Quantum Tomorrow'. Its chapters run from J. J. Thomson (6:18) and Rutherford (8:13) to John Nicholson (12:15), a rival atom-builder this lesson leaves out, so you see what Bohr took from, and owed to, the people around him.