Answer:
Step-by-step explanation:
Distance of each of the charges from the center are equal . If this distance be d
d = .5 x length of diagonal of square
length of diagonal = 4√2
d = .5 x 4√2
= 2√2
potential at a point
V = k Q / r where k is a constant , Q is charge and r is distance of the point from the charge .
k = 9 x 10⁹
Total potential =


=

= 9 √2 x 10⁹ V .