A small ball of mass `2 xx 10^-3 kg`, having a charge `1 mu C`, is suspended by a string of length `0.8 m`. Another identical ball having the same charge is kept at the point of suspension. Determine the minimum horizontal velocity that should be imparted to the lower ball so that it can make a complete revolution.

Options

A. `6.2 ms^(-1)`
B. `9.8 ms^(-1)`
C. `11.6 ms^(-1)`
D. `5.86 ms^(-1)`

Answer

D