# Electric field strength and speed

1. Feb 7, 2008

### mary_ellen

The electric field strength is 1.70×104 inside a parallel-plate capacitor with a 1.40 spacing. An electron is released from rest at the negative plate.

What is the electron's speed when it reaches the positive plate?
You need to combine Forces with Kinematics. We know that F = KE/r and also know that $$(v_{f})^2 = (v_{i})^2 + 2ad$$ and of course, newton's second law: F = ma. You have everything you need, just use some basic algebra, and that's it.