A particle of mass M and charge q, initially at rest, accelerated by a uniform electric field E through a distance D and is then allowed to approach a fixed static charge Q of the same sign. The distance of the closest approach of the charge q will then be

Options

A. `(qQ)/(4 pi epsilon_0D)`
B. `(qQ)/(4 pi epsilon_0ED)`
C. `(qQ)/(2 pi epsilon_0D^2)`
D. `(qQ)/(4 pi epsilon_0D^2)`

Answer

B

Explanation

Conservation of energy
`(qE)D=1/(4 pi epsilon_0).(qQ)/(r_0) implies r_0 =Q/(4piepsilon_0ED)`