Question

An alpha particle approaches a gold nucleus in Geiger-Marsden experiment with kinetic energy K. It momentarily stops at a distance d from the nucleus and reverses its direction. Then d is proportional to:

(A) \(\frac 1{\sqrt K}\)

(B) \(\sqrt K\)

(C) \(\frac 1K\)

(D) \(K\)

Answer 1

Correct option is (C) \(\frac 1K\)

\(K.E. = P.E.\)

\(K.E. = 2e\left( \frac {KZe}r\right)\) 

\(r = \frac {2KZe^2}{K.E}\)