Several identical point charges (shown in red) are placed on a circular disk (shown in blue) so as to minimize the electrostatic energy of the system. Obviously, single charge can be placed anywhere as depicted in Fig. (a), while a pair of charges will occupy opposite sides of the diameter of the circle, as in Fig. (b). Similarly, three charges will form an equilateral triangle, as in Fig. (c). What can you say about the geometric arrangement of 4, 5, 6, ... charges?

For 4 charges it will form a square and for more it will form regular polygons

ya dats right...but wot do you think will we ba able put infinite charges or wot will happen in case of around 1000 charges?????????????