A 40-μC Charge Is Situated at the Origin of an Xy-Coordinate

A 4.0-μC charge is situated at the origin of an xy-coordinate system. What is the potential difference between a point x = 4.0 m and y = -4.0 m because of this charge?

A) 18 × 10³ V
B) -18 × 10³ V
C) 0 V
D) 36 × 10³ V
E) -36 × 10³ V