Answer to Question #65291 in Electric Circuits for Helen

Question

An electron is fired horizontally with an initial velocity of 4.20 × 106 m/s between a
pair of horizontal plates. The plates are separated by a distance of 1.20 mm and are
charged to have a potential difference of 120 V, with the bottom plate being at the
higher potential. If the electron is midway between the plates when it is fired, how far
from its entry point will it strike the bottom plate? You may ignore the acceleration
due to gravity in this problem so that the force on the electron is entirely due to
electrostatics (but think about why this assumption is OK!).