Problem 72-7    Source:  Problem elaborated by the author of the site.

Let two electric charges, A and B, be separated by a distance of d = 10 cm. If payload A is loaded with 12 µC and payload B with -5 µC, find the value of the potential at the midpoint of the line connecting the two charges.

Solution of the Problem 72-7   

Let's recall the eq. 72-10, which says that the value of the potential is given by the algebraic sum of the potentials of each charge. Review the equation below

Since we want the potential at the midpoint, so for the two charges r = 0.05 m. Substituting the values into the equation we have:

Carrying out the calculation, we find