1. I am then asked to pick the magnitude and direction of E at each point. For all points, I can correctly deduce the direction because the E field points in the direction of decreasing potential. However, what are they doing to calculate the magnitude here? I know the magnitude is 500V/m for A, and I could deduce the correct answers for the rest of the points relative to A. 2. V = U/q = Ed 3. Since I'm not given the charge of a particle at those points, I must need to use some value for d to compute E since V is known for each point. But what d do I use?