A bullet of mass m and charge `q` is fired towards a solid unifromly charged sphere of redius `R ` and total cbharge ` + q`. If it strikes the surface of sphere with speed `u`, find the minimum speeed `u` so that it can penetrate through the sphere , (Neglect all resistance forces or friction acting on bullet except electrositatic forces )
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A. `(q)/(sqrt(2 pi varepsilon_(0)mR)`
B. `(q)/(sqrt(4 pi varepsilon_(0)mR)`
C. `(q)/(sqrt(8 pi varepsilon_(0)mR)`
D. `(sq)rt3q/(sqrt(4 pi varepsilon_(0)mR)`