Three point charge `Q,4Q` and `16Q` are placed on a straight line `9`cm long.Charges are placed in such a way that the system has minimum potential energy .Then

Options

A. `4Q` and `16Q`must be at the ends and `Q` at a distance of `3cm` form `16Q`
B. `4Q` and `16Q`must be at the ends and `Q` at a distance of `6cm` form `16Q`
C. Electric field at the position of `Q` is zero
D. Electric field at the position of `Q` is `(Q)/(4piepsilon_(0))`

Answer

B,C

Explanation

`U=Sigma(1)/(4piepsilon_(0))(q_(1)q_(2))/(r)`