Consider a system of three charges `q//3, q//3, and -2q//3` placed at points A, B, and C, respectively, as shown in figure. Take O to be the center of the circle of radius R and angle CAB` = 60^@`. Then

Options

A. The electrical field at point O is `(q)/(8 pi epsi_(0)R^(2))`
B. The potential energy of the system is zero
C. The magnitude of the force between the charges at point C and B is `(q^(2))/(5 4pi epsi_(0) R^(2))`
D. The potential at point O is `(q)/(12pi epsi_(0) R)`

Answer

C

Explanation

Distance `BC=ABsin60^(@)=(2R)(sqrt3)/(2)=sqrt(3)R" "therefore" "|Fe_(BC)|=(1)/(4piepsi_(0))((q//3)(2q//3))/((sqrt(3)R)^(2))=(q^2)/(54piepsi_(0)R^(2))`