A small sphere of mass m = 0.6 kg carrying a positive charge q = 80μC is connected with a light, flexible, and inextensible string of length r = 30 cm and whirled in a vertical circle. If a horizontal rightward electric field of strength E = 105 NC^−1 exists in the space, calculate the minimum velocity of the sphere required at the highest point so that it may just complete the circle (g=10 ms^−2).
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