It is four times the potential due to a charge at a single corner.
Your equation
1/4¦Ð = 8.99 ¡Á 10^9 N ¡¤ m2/C2
is obviously incorrect.
The distance from the center of the square to a corner is R = 1.414 m
The potential due to a single corner charge is
kQ/R
where Q = 6.00*10^-6 C
k = 8.99 ¡Á 10^9 N¡¤m^2/C^2
Four equal +6.00-μC point charges are placed at the corners of a square 2.00 m on each side. ( = 1/4π = 8.99 × 109 N · m2/C2)
(a) What is the electric potential (relative to infinity) due to these charges at the center of this square?
4 answers
153kv
153 kV is the correct answer
You must check if the problem says that charges are equal in magnitude and SIGNS, if all the charges are positive then you have the answer