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Physics · 2024 · 2 marks
AtomsAlpha-particle Scattering and Rutherford’s Nuclear Model of Atom2 marksUnderstandvery short answer
CBSE 2024 · Region 2 · Set 3 · Q27
Draw a schematic arrangement of Geiger-Marsden experiment. Briefly explain the conclusions drawn from the observations about the structure of an…
Draw a schematic arrangement of Geiger-Marsden experiment. Briefly explain the conclusions drawn from the observations about the structure of an atom. Define 'distance of closest approach' in this case.
Marking-scheme solution
(b)
Entire positive charge and most of the mass of the atom are concentrated in the nucleus.
Electrons move in orbits about the nucleus just as planets around the sun.
Size of the nucleus is about $\displaystyle 10^{-15} \mathrm{~m}$ to $\displaystyle 10^{-14} \mathrm{~m}$.
Most of the space in an atom is empty.
(c)
The distance of the $\displaystyle \alpha$ particle from the centre of the nucleus at which the whole of the initial kinetic energy of the particle gets converted into electric potential energy.
OR
The distance of the $\displaystyle \alpha$ particle from the centre of the nucleus at which it stops momentarily and reverses its direction.
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CBSE Class 12 Physics past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.