An electron in a trajectory motion between the center of two plates

[Alfaraj]

Homework Statement

An electron with an initial velocity of 5.6x107 m/s in the x-direction moves along a trajectory that takes it directly between the center of two 20 cm x 20 cm plates separated by 1 cm. The plates are connected to a high voltage power supply so that the potential difference between them is 500V. What is the magnitude of the y-component of the electron’s velocity when it leaves the plates? (Answer in units of ANSWER x 107 m/s.)

Homework Equations

Kf + Uf = Ki + Ui
deltaU = q * delta V

The Attempt at a Solution

In this question I figured out the final velcity in the x-direction using the condervation of energy approach. I figured out the change in potential energy by multiplying the potential difference by the elementary charge. How do I obtain the final y-direction velocity?

 

[Stonebridge]

The x component of the electron's motion is unaffected by the force on it due to the field between the plates. Use this to calculate how long the electron is between the plates.
The force on the electron due to the field acts in the y direction for this time and accelerates the electron in the y direction. Use this acceleration, and the time, to find the final y-direction velocity.