An infinite line cahrge is perpendicular to the plane of the figure having linear charge density `lamda`, A partcle having charge Q and mass m is projected in the field of the line cahrge fromo point P. the point P is at a distance R from the line cahrge and velocity given tot he particle is perpendicular tot he radial line at P (see figure)
(i). Find the speed of the particle when its distance from the line cahrge grows the `etaR(eta gt 1)`
(ii). Find the velocity component of the particle along the radial line (joining the line charge to the particle) at the instant its distance becomes `etaR`.

Answer

(a) `V=sqrt(V_(0)^(2)+(lamdaQ)/(pi epsi_(0)m)ln eta)`
(b). `V_(r)=sqrt(V_(0)^(2)(1-(1)/(eta^(2)))+(lamdaQ)/(pi epsi_(0)m)ln eta)`