The figure below shows an electron entering a parallel-plate capacitor with a speed of v = 5.20 x 10^6 m/s. The electric field of the capacitor has deflected the electron downward by a distance of d = 0.614 cm at the point where the electron exits the capacitor. The length of the capacitor is 2.25 cm. (a) Find the magnitude of the electric field in the capacitor. (b) Find the speed of the electron when it exits the capacitor.
I tried to solve for the electric field using E=kq/r^2 but my answer was off by orders of magnitude. For the radius, I used the length of the capacitor/2 b/c the electron ends up making a parabolic shape. For the final velocity, I tried using the equation v^2=Vo^2+2gdelta y but my answer was not correct for that either.