[10] (3) A velocity selector having uniform perpendicular electric and magnetic fields is shown in Figure. The electric field is provided by a 150 V DC battery connected across two large parallel metal plates that are 4.50 cm apart. [2.5] (3.a) Find the electric field E between the plates of the selector. [2.5] (3.b) What must be the magnitude of the magnetic field B so that charges + q having a velocity of 3.25 km/s perpendicular to the fields will pass through undeflected? [2.5] (3.c) Show how the magnetic field should point in the region between the plates (into the page, out of the page, to the left, to the right, up or down). [2.5] (3.d) Solve (3.b) and (3.c) when the charges are negative (i.e. - q). 150 V + 4.50 cm V