Four equal charges q are placed at the four corners of a square of length of each side a. What charge should be kept at the middle of the square so that the system is in equilibrium ?

Four identical charges each .q. are placed at four corners of a square of side .a.. Find the charge to be placed at the centre of the square so that the system of charges is in equilibrium

Four identical charges i.e. q is placed at the corners of a square of side a . The charge Q that must be placed at the centre of the square such that the whole system of charges in equilibrium is

Four charges, each of value q, are placed at the four corners of a square of side a. What is the potential at the centre of the square

Equal charges q are placed at the four corners A,B,C,D of a square of length a . The magnitude of the force on the charge at B will be

Equal charges q are placed at the four corners A B C D of a square of length a. The mangniture of the force on the charge at B will be

Three point charges q are placed on vertices of an equilateral triangle of side length a . The charge Q that should be kept at centroid of triangle such that the system is in equilibrium is equal to