1. Two particles of positie charge q, are fixed in place on the y-axis, one at y = d and the other at y = -d. Write an expression that gives the magnitude of E of the net electric field at points on the x-axis given by x = αd is some value between x = -α and +α

2. A charge of 20 nC is uniformly distributed along a straight rod of length 4.0 m that is bent into a circular arc with a radius of 2.0 m. What is the magnitude of the electric field at the center of curvature of the arc?

3. Four point charges are located at the corners of a square with each side of length l = 5.0 cm, as shown in the figure from the last problem. Charge q1 = 10.0 nC, q2 = -20 nC and charge q3 = +20 nC q4 = -10.o nC. What is the electric fieldin unit vector notion due to all the charges at point P? Sketch a diagram a showing the electric field lines for charges 3 and 4.