In the diagram shown the charge `+Q` is fixed. Another charge `+2q` and mass M is projected from a distance R from the fixed charge. Minimum separtion between the two charge if the velocity becomes `1/sqrt3` time of the projected velocity, at this moment is (Assume gravity to be absent)

Options

A. `sqrt(3)R`
B. `(sqrt(3)R)/(2)`
C. `(R )/(2)`
D. `4R`

Answer

B

Explanation

Separation between them is minimum when veclocity is perpendicular to line joining the two charges rArr Applying conservation of angular momentum
`mV_(0)sin30 R=mVd`
`mV_(0)(1)/(2)R=m(V_(0))/(sqrt(3))d rArrd=(sqrt(3)R)/(2)`