question_answer

A small sphere of mass m and carrying a charge q is attached to one end of an insulating thread of length a, the other end of which is fixed at (0, 0) as shown in figure. There exists a uniform electric field \[\vec{E}=-\text{ }{{\vec{E}}_{0}}\text{ }\hat{j}\] in the region. The minimum velocity which should be given to the sphere at (a. 0) in the direction shown so that it is able to complete the circle around the origin is (There is no gravity)

A) \[\sqrt{\frac{5q{{E}_{0}}a}{m}}\]        

B)        \[\sqrt{\frac{3q{{E}_{0}}a}{m}}\]

C) \[\sqrt{\frac{q{{E}_{0}}a}{m}}\]          

D)        \[2\sqrt{\frac{q{{E}_{0}}a}{m}}\]