# Homework Help: Eletricity, question from Brazil

1. Feb 13, 2010

### Aldo Gondim

Hello, I'm with a doubt, and my teacher don't know how to solve, I translated this question to English so it can have some mistakes, please help me!

1. The problem statement, all variables and given/known data
(ITA) In a laboratory experiment, electrons are emitted by a metal filament F with virtually no initial velocity and are accelerated through the region I by a potential difference U1 25 × 10 ³ V, applied between F and the perforated plate P. They emerge from the hole of the plate with horizontal velocity and penetrate the region II, where they are forced to cross the uniform electric field of a capacitor whose plates are 5.0 cm long and are separated by a distance d = 0.50 cm as shown. What is the maximum value of U2 ddp between the plates of the capacitor that still allows some electrons reach the region III, where there is electric field?
Is given the figure:
http://img16.imageshack.us/img16/9923/fisita.jpg [Broken]

2. Relevant equations
How can I find the tension? Using T=q.U

3. The attempt at a solution
Trying to decompound the vectors but didn't work

Thanks

Last edited by a moderator: May 4, 2017