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Physics20251.5 marksShort answerAtoms

Solve the following.

A charged particle of energy, E = 1/2mv² bombards a heavy target of charge Ze, then shows with the…

A charged particle of energy, $E = \frac{1}{2}mv^2$ bombards a heavy target of charge Ze, then shows with the help of a graph how the distance of the closest approach varies with the mass of the particle.

Answer

Answer

At the closest approach the whole kinetic energy has become electrostatic potential energy: $E = \frac{1}{4\pi\varepsilon_0}\frac{Zeq}{r_0} \Rightarrow r_0 = \frac{Zeq}{4\pi\varepsilon_0 E}$ The energy $E = \frac{1}{2}mv^2$ is fixed, so $r_0$ does not depend on the mass of the particle. The graph of $r_0$ against $m$ is a straight line parallel to the mass axis.