Electricity and Magnetism

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The Potential Due to Four Charges on the Side of a Square


Figure 1 depicts a square of side length $s = 20.0$ mm on whose corners are arrayed four charges. Each charge has the same magnitude of $q = 1.00$ nC. Three of the charges are positive and one of them is negative, so that $q_1 = q_2 = q_4 = +q$ and $q_3 = -q$. Four points are labeled on the outer square; points $A$, $B$, $C$, and $D$. Each of these points lies at the center point of one side of the outer square.

Figure 1. “Timothy Black. Created for Albert.io. Copyright 2016. All rights reserved.”

What is the electric potential at point $C$?


$V = 804$ Volts.


$V = \left(1.61 \times 10^4\right) \hat{x} – \left(1.80 \times 10^5\right) \hat{y}$ Volts.


$V = 599$ Volts.


$V = 804 \hat{x} – 804 \hat{y}$ Volts.