In designing a velocity selector that uses uniform perpendicular electric and magnetic fields, you want to select positive ions of charge that are traveling perpendicular to the fields at 8.75 km s. the magnetic field available to you has a magnitude of 0.550 t. (a) what magnitude of electric field do you need? (b) show how the two fields should be oriented relative to each other and to the velocity of the ions. (c) will your velocity selector also allow the following ions (having the same velocity as the ions) to pass through undeflected: (i) negative ions of charge (ii) positive ions of charge different from