3. (1 pt) Three charges are placed in a plane, with 1C at x=0 cm, y = 3cm, -2C at x=6cm, y=0cm, and +4C at (x,y) = (0cm, 0cm)

1 C (0, 3cm)

4 C (0cm, 0 cm) -2 C (6cm, 0cm)

(a) Find the electrical potential at the point (x,y) = (6cm, 3cm) due to these 3 charges.

(b) A fourth charge of -4C is placed at (x,y) = (6cm, 3cm). Find the total electrical potential energy of this charge due to the other 3.

4. (2 pts) Start with the charge configuration of problem 3.

a. Find a position and value of a fifth charge that can be placed in the same plane as the other charges so that the total electrical potential energy of the fourth charge is zero.

b. Is it possible to find a solution for the fifth charge with it lying outside the plane of the other four charges? Why or why not?