At a scientific institute, researchers have recently uncovered an empirical equation that describes the electric potential between two electrodes: V(x) = 100 ln(1 + x/5). Here, x is measured in meters, and it is the distance originating from the first electrode and extending towards the second electrode. The separation between the electrodes is 10 meters. Determine the magnitude of the electric field strength when positioned 3.5 meters away from the first electrode.