. A bob of mass m = 100 gm having charge q = 50mC connected with

A bob of mass m = 100 gm having charge q = 50mC connected with a non-conducting string of length / = 1 is whirled in vertical plane with minimum speed such that it can complete a circular path in space where electric field of strength E =  2 × 10⁴ N/C is present as shown in figure. The velocity of bob at the point where tension in string become zero is