Alpha Scattering & Nuclear Atom Challenge
25 NEET-standard questions on Thomson’s plum pudding model, the Geiger–Marsden α-particle scattering experiment and Rutherford’s nuclear atom. Answer each one. If you get it wrong, Vidya Ma’am explains it with an animated movie you can control, a slider to play with, and a step-by-step solution. Then try again.
NCERT Physics XII Part II · Ch. 12 · pp. 290–293Keys: A–D or 1–4 to answer
🧠 Formula memory tricks (open before you start)
Thomson vs RutherfordThomson (1898): positive charge spread through the atom, electrons like seeds. Rutherford: tiny nucleus with all the positive charge and most of the mass.
Experiment5.5 MeV α · gold foil 2.1×10⁻⁷ m · ZnS screenGeiger and Marsden, about 1911
Counts0.14% beyond 1° · 1 in 8000 beyond 90°most pass straight: atom mostly empty
Sizesatom 10⁻¹⁰ m · nucleus 10⁻¹⁵ to 10⁻¹⁴ mratio 10⁴ to 10⁵; volume fraction ≈ 10⁻¹⁵
α-particleHe nucleus: charge +2e, mass number 4. Gold: Z = 79, about 50 times heavier.electrons are too light to deflect α
Unit1 MeV = 1.6×10⁻¹³ J5.5 MeV = 8.8×10⁻¹³ J
right first tryfixed after explanationstill to fix
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