Consider an electron with an initial speed v0 = 29 Mm/s (1 Mm = 1 megameter = 1000 km = 1E6 m) that is traveling parallel to an electric field (v0||E) of magnitude E = 7.1 kN/C (1 kN = 1 kilonewton = 1E3 N). How long will it take (what duration T, in microseconds) for the electron to return to its starting point?