What happens to the electron's trajectory?
The electron is shot between the plates with some initial velocity as shown below.
Consider the forces acting on the electron when it is in the region between
the charged plates. In which direction does the electric field point? In which
direction does the force acting on the electron point?
In the region between the two charged plates, the electric field generated
by the charged plates points downward. Recall that electric field lines point
from positive to negative charges. The force on the electron is pushing the electron
upward. What will the electron trajectory look like then?
The upward force will accelerate the particle upward causing a bend in its
trajectory.
