You can find the mass of a test charge by shooting it horizontally in between a set of large parallel plates, as shown in the figure. The voltage (electric potential difference) between the plates can be adjusted so that the charged particle does not deflect from its original trajectory. A helium nucleus of charge +2e and mass 6.6 x 10-27 kg is fired into such a par- allel plate system. Assume a constant electric field between the plates. (a) If the charge is not to deflect, what must be the sign of the charges on each of the plates - draw them on the plates in the figure