Question

Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon such that the electric field at O is double the electric field when only one positive charge of same magnitude is placed at R. Which of the following arrangements of charge is possible for,P,Q,R,S,T and U respectively?

• A. +,-,+,-,-,+
• B. +,-,+,-,+,-
• C. +,+,-,+,-,-
• D. -,+,+,-,+,-

Answer 1

The correct option is D -,+,+,-,+,-

If same charges are placed in diagonally opposite vertices the electric field due to the same charges gets cancelled.
$\therefore$ charge at R and U must be of opposite sign and charges at P, S and Q, T must be of same sign
$\therefore$ only option 4 is satisfying.