An lon is placed in the region between the plates of a parallel-plate capacitor. The voltage between the plates is 150 V, and the plates are separated by a distance of 4 cm. If the resulting electrostatic force on the lon is 1.8 x 10 N toward the positive plate, then what Is the charge on this lon (In terms of the elementary charge, e) ? 6 -4e -2e +2c a -3e 5 +60 +30 0 -be