Question

The figure shows three charges q1, q2 and q3 situated at corners of a rectangle of sides a 14.0 cm and b 8.0 cm. 2 For q1 = 5.80 μC, q2 =-5.80 pC, and q3 = 2.50 μC find the electric potential at the center of the rectangle 2.79×105 V You are correct. Previous Tries Continuing with the figure above, how much of the electric energy of the system would be expended in moving q3 to infinity while q1 and 42 remain in their positions? Submit Answer Incorrect. Tries 1/99 Previous Tries

Please, give me the right answer to the B part, and show workings pls

Answer 1

potential energy between two charges is $\frac{KQ_{1}Q_{2}}{r}$ so find the potential energy of the third charge whe it is at infinity it will be 0

so net potential enrgy due to 1 &2 is $KQ_{3}\left ( \frac{Q_{1}}{r_{13}} + \frac{Q_{2}}{r_{23}} \right )$ = 9 x 10⁹ x2.5x10^-6 (5.8x10^-6 /0.08-5.8x10^-6 /0.1624)=0.815J