In the Rutherford's experiment, a particles were bombarded towards the copper atoms so as to arrives a distance of `10^(-13)` metre from the nucleus of copper and then getting either deflected or traversing back. The a-particles did not move further closer
The velocity of the a-particles must be

Options

A. `8.32 xx 10^(8)cm//sec`
B. `6.32 xx 10^(8)cm//sec`
C. `6.32 xx 10^(8)m//sec`
D. `6.32 xx 10^(8)km//sec`

Answer

B

Explanation

At the distance of closest approach
`v^(2) = (2Ze2e)/(4piepsilon_(0)r_(0)) xx (1)/(m)` hence, substituting the value of `m = 4, Z = 29, e = 1.66 xx 10^(-19), r_(0) = 10^(-13)m`