A point charge `q_(0)` is placed at the centre of uniformly charges ring of total charge Q and radius R. If the point charge is slightly displaced with negligible force along axis of the ring then find out its speed when it reaches a large distance.

Explanation

Only electric force is acting on `q_(0)`
`:. W_(el) = Delta K = (1)/(2)mv^(2) - 0`
`rArr` Now `W_(el))_(c rarr oo) = q_(0) V_(c ) = q_(0). (KQ)/(R )`
`:. (Kq_(0)Q)/(R ) = (1)/(2)mv^(2)`
`rArr v = sqrt((2Kq_(0)Q)/(mR))`