In an alpha particle scattering experiment distance of closest approach for the $\alpha$ particle is $4.5…

In an alpha particle scattering experiment distance of closest approach for the $\alpha$ particle is $4.5 \times 10^{-14} \mathrm{~m}$. If target nucleus has atomic number 80 , then maximum velocity of $\alpha$ - particle is _______ $\times 10^5 \mathrm{~m} / \mathrm{s}$ approximately. $\left(\frac{1}{4 \pi \epsilon_0}=9 \times 10^9\right.$ SI unit, mass of $\alpha$ particle $\left.=6.72 \times 10^{-27} \mathrm{~kg}\right)$

Solution

$\begin{aligned} v & =\sqrt{\frac{4 \mathrm{KZe}^2}{\mathrm{mr}_{\text {min }}}} \\ & =\sqrt{\frac{4 \times 9 \times 10^9 \times 80}{6.72 \times 10^{-27} \times 4.5 \times 10^{-14}}} \times 1.6 \times 10^{-19} \\ & =9.759 \times 10^{25} \times 1.6 \times 10^{-19} \\ & =156 \times 10^5 \mathrm{~m} / \mathrm{s}\end{aligned}$

Asked in: JEE Main 2024 (08 Apr Shift 1)

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