... 22 Electric Potential For a Point Above One End of the Rod When a point P is located at a distance a from one of the rod’s ends, see Fig 22 .17, we can perform similar calculations to find that: ... Therefore: V = 2kλ ln x + a2 ) (22 .48) L /2 (L /2) 2 + a2 ) − ln (a) L /2 + (L /2) 2 + a2 a (22 .49) When we use the fact that the total charge Q = λL, we get: V = L /2 + 2kQ ln L (L /2) 2 + a2 a (22 .50) 7 52 ... potential energy of each pair and add them algebraically For instance, the total potential energy of three charges q1 , q2 , and q3 is: q1 q2 q1 q3 q2 q3 + + r 12 r13 r23 U=k (22 .31) Example 22 .5 Two...