Atomic & Nuclear Lab

Everywhere

• Topic tabs (under the title) switch between simulations in this lab. Some topics have smaller buttons under the stage for their screens.
• Teach shows live equations with the current numbers and "What to notice" points. Practice gives a numeric problem and a quiz.
• Move the sliders or tap the chips in the right-hand panel. The readings box updates live.
• Pause / Restart control the animation. Clean view hides everything except the stage, for projecting or recording; press Esc to leave it.
• In Practice, type a number (e.g. 12.5 or 3.2e-10), press Check or Enter. Show it on the stage sets the simulation to that problem.
• Nothing is saved: scores reset when the page is reloaded.

Language

• Choose English or বাংলা once on the home page (top right); every lab then opens in that language — tabs, controls, readings, equations, notes, problems and quizzes.

Rutherford scattering

• α-particle scattering: a stream of α-particles past a gold, silver, copper or aluminium nucleus, with the deflection-angle histogram and the flashes on the screen; set the α energy and the beam width.
• Plum pudding vs nucleus: Thomson's and Rutherford's atoms side by side with α-particles passing each.
• Closest approach: a head-on α slowing to a stop at r₀ = 2kZe²/K, with the KE/PE bars.

Bohr model

• Orbits & jumps: orbits drawn to scale (r ∝ n²), the electron jumping from n₂ to n₁ and emitting a photon of the right colour; rₙ, vₙ, Eₙ for both levels.
• Energy levels: the level diagram with the transition arrow, ΔE, f and λ.
• Hydrogen spectrum: Lyman, Balmer, Paschen and Brackett lines on a log wavelength axis, the visible band, the first lines and the series limit.

The nucleus

• Size & density: pick a nuclide; R = 1.2 A^⅓ fm, the R–A^⅓ line and the constant nuclear density.
• Mass defect & binding energy: separate nucleons versus the bound nucleus, Δm and BE = Δm × 931.5 MeV from real atomic masses.
• Binding energy per nucleon: the BE/A curve with the nuclides marked, the iron peak and the fusion and fission arrows.

Radioactivity

• Decay law & half-life: 400 nuclei decaying at random beside the N₀e^(−λt) curve; set the half-life and press Restart to run again.
• α, β and γ: the three rays in a magnetic field, an electric field or none, and their stopping by paper, aluminium and lead.
• Activity & mean life: pick an isotope and a sample mass; N, λ, A = λN in Bq and Ci, and τ = 1.44 T½.

Fission & fusion

• Nuclear fission: a slow neutron splitting ²³⁵U into Ba + Kr (or Xe + Sr) with the mass-defect energy account.
• Chain reaction: the tree of fissions for k = 1, 2 or 3 over several generations — reactor versus bomb.
• Nuclear fusion: D + T colliding at a temperature you set, the Coulomb barrier picture and the 17.6 MeV energy account.

Full guide with teaching tips: User manual (also as a PDF).