The three charges shown in Figure 20-25 are held in place as a fourth charge, q, is brough...

The three charges shown in Figure 20-25 are held in place as a fourth charge, q, is brought from infinity to the point P. The charge q starts at rest at infinity and is also at rest when it is placed at the point P. (a) If q is a positive charge, is the work required to bring it to the point P positive, negative, or zero? Explain. (b) Find the value of (/ if the work needed to bring it to point P is −1.3 × 10–11 J.

FIGURE 20-25 Problem