1. The problem statement, all variables and given/known data Two particles are fixed to an x axis: particle 1 of charge -1.23 x 10-7 C is at the origin and particle 2 of charge +1.23 x 10-7 C is at x = 15.5 cm. Midway between the particles, what is the magnitude of the net electric field? 2. Relevant equations E=kQ/r^2 and/ or E=2kQ/r^2 3. The attempt at a solution I used the first equation and I got 3.68e5 N/C then I used the second equation because there are two charges and I got 3.93e5 N/C. Both of these answers were marked wrong and I don't know why. Any help? Thanks.