# NEET Physics Atoms Questions Solved

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NEET - 2009

In a Rutherford scattering experiment when a projectile of charge ${Z}_{1}$ and mass ${M}_{1}$ approaches a target nucleus of charge ${Z}_{2}$ and mass ${M}_{2},$ the distance of closest approach is ${r}_{0}$. The energy of the projectile is

(a) directly proportional to ${M}_{1}×{M}_{2}$

(b) directly proportional to ${Z}_{1}{Z}_{2}$

(c) inversely proportional to ${Z}_{1}$

(d) directly proportional to mass ${M}_{1}$

A particle of mass ${M}_{1}$ and charge ${z}_{1}$ possess initial velocity u, when it is at a large distance from the nucleus of an atom having atomic number ${z}_{2}$. At the distance of closest approach, the kinetic energy of particle is completely converted to potential energy. Mathematically,

$\frac{1}{2}{M}_{1}{u}^{2}=\frac{1}{4{\mathrm{\pi \epsilon }}_{0}}\frac{{z}_{1}{z}_{2}}{{r}_{0}}$

So the energy of the particle is directly proportional to ${z}_{1}{z}_{2}$.

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