An ion source is producing 6Li ions, which have charge +e and mass 9.99 x 10-27 kg. The ions are accelerated by a potential difference of 10 kV and pass horizontally into a region in which there is a uniform vertical magnetic field of magnitude B = 1.2T. Calculate the strength of the smallest electric field, to be set up over the same region that will allow the 6Li ions to pass through undefeated.