The potential energy at x = 8 m is -2000 V and at x = 2 m is +400 V. What is the magnitude and direction of the electric field? 400 V/m directed parallel to the +x-axis 200 V/m directed parallel to the +x-axis 300 V/m directed parallel to the +x-axis 600 V/m directed parallel to the +x-axis 500 V/m directed parallel to the +x-axis