oppositely charged parallel plates are separated by 7.5 [mm]. a potential difference of 300 [v] exists between the plates. a) what is the magnitude of the electric field between the plates? b) what is the magnitude of the force on an electron between the plates? c) how much work must be done on the electron to move it to the negative plate if it is initially placed 1 [mm] from the positive plate? hint: this is asking about the external work required, not the work done by the electric field. in fact, this is moving the electron opposite of its desired direction.