Charge q is placed at each of the corners of a hexagon of side r. The potential at its centre is ________.(write the formula in the blank)

Six charges +q each are placed at the corners of a regular hexagon of each side a. The electric field at the centre of the hexagon is

Charges 1mu coul each are placed at the corners of a squares of side 9 cm. Calculate the potential at the centre of the square.

A charge q is placed at the centre of a cube. The flux associated with each wall of the cube is

Four point charges each of 10 nano coulomb are placed at the four corners of a square of side 2 m each. Find the neat potential at the centre of the square.