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AP EAMCET · PHYSICS · Atomic Physics

Assertion (A) The impact parameter for \(\alpha\)-particles by \(180^{\circ}\) is zero.
Reason (R) Zero impact parameter means that the \(\alpha\)-particles tend to hit the centre of the nucleus.

  1. A Both \(\mathrm{A}\) and \(\mathrm{R}\) are true and \(\mathrm{R}\) is a correct explanation for \(A\).
  2. B Both \(\mathrm{A}\) and \(\mathrm{R}\) are true but \(\mathrm{R}\) is not a correct explanation for \(\mathrm{A}\).
  3. C \(\mathrm{A}\) is true but \(\mathrm{R}\) is false.
  4. D \(\mathrm{A}\) is false but \(\mathrm{R}\) is true.
Verified Solution

Answer & Solution

Correct Answer

(A) Both \(\mathrm{A}\) and \(\mathrm{R}\) are true and \(\mathrm{R}\) is a correct explanation for \(A\).

Step-by-step Solution

Detailed explanation

Impact parameter, \(b=\frac{z e^2 \cot \frac{\theta}{2}}{4 \pi \varepsilon_0\left(\frac{1}{2} m v^2\right)}\) For \(\theta=180^{\circ}, \cot 90^{\circ}=0\), impact parameter, \(b=0\) Hence, \(\alpha\)-particles tend to hit the centre of nucleus. Thus, both \(\mathrm{A}\) and…