Q.

Six point charges are kept 60° apart from each other on the circumference of a circle of radius R as shown in figure. The net electric field at the center of the circle is ______.

(ε0 is permittivity of free space)           [2026]

1 -(5Q8πε0R2)(i^-3j^)  
2 Q4πε0R2(3i^-j^)  
3 -5Q8πε0R2(i^+3j^)  
4 -Q4πε0R2(3i^-j^)  

Ans.

(4)

Let kQr2=E0

Enet=2E0cos30°(-i^)+2E0sin30°(j^)

=2kQr2[32(-i^)+12j^]

=-Q4πε0r2(3i^-j^)