Question
Four charges $+q_1+2 q_1+q$ and $-2 q$ are placed at the corners of a square $A B C D$ respectively. The force on a unit positive charge kept at the centre $O$ is
Four charges $+q_1+2 q_1+q$ and $-2 q$ are placed at the corners of a square $A B C D$ respectively. The force on a unit positive charge kept at the centre $O$ is