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Physics · 2024 · 3 marks
CBSE 2024 · Region 4 · Set 1 · Q24
Draw the graph showing variation of scattered particles detected ( N ) with the scattering angle ( θ ) in Geiger-Marsden experiment. Write two…
Draw the graph showing variation of scattered particles detected ( N ) with the scattering angle ( $\displaystyle \theta$ ) in Geiger-Marsden experiment. Write two conclusions that you can draw from this graph. Obtain the expression for the distance of closest approach in this experiment. 
Marking-scheme solution
Two conclusions:
(i)
Most of an atom is empty space.
(ii)
Almost the entire mass and entire positive charge is concentrated in a very small region called the nucleus.
At the distance of closest approach:
$\displaystyle E_{k}=E_{P}$
$\displaystyle K=\frac{1}{4 \pi \varepsilon_{0}} \frac{(Z e)(2 e)}{d}$
$\displaystyle d=\frac{1}{4 \pi \varepsilon_{0}} \frac{\left(2 Z e^{2}\right)}{K}$
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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.